1

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

AMENDMENT NO. 1 TO
SCHEDULE 13D
Under The Securities Exchange Act of 1934

COMPANIA BOLIVIANA DE ENERGIA ELECTRICA S.A. -
BOLIVIAN POWER COMPANY LIMITED
--------------------------------------------------------------------------------
(Name of Issuer)

Common Shares, Without Nominal or Par Value
--------------------------------------------------------------------------------
(Title of Class of Securities)

204425 102
--------------------------------------------------------------------------------
(CUSIP Number)

David H. Peterson
Compania Boliviana de Energia Electrica S.A. -
Bolivian Power Company Limited
Obrajes, Ave. Hernando Siles #5635
Entre Calles 10 y 11
La Paz, Bolivia
--------------------------------------------------------------------------------
(Name, Address and Telephone Number of Person Authorized
to Receive Notices and Communications)

with a copy to:

Frank Voigt, Esq.
Dorsey & Whitney LLP
Pillsbury Center South
220 South Sixth Street
Minneapolis, Minnesota 55402-1498
(612) 340-2781

October 26, 1999
Date of Event wich Requires Filing of this Statement

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition that is the subject of this Schedule 13D, and is filing this
schedule because of ss.240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the
following box. [  ]

2

CUSIP NO. 204425 102

--------------------------------------------------------------------------------
1   NAMES OF REPORTING PERSONS/I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS
(ENTITIES ONLY)

Tosli Acquisition B.V./N/A
--------------------------------------------------------------------------------
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
(See Instructions)
(a) [X]
(b) [ ]
--------------------------------------------------------------------------------
3   SEC USE ONLY

--------------------------------------------------------------------------------
4   SOURCE OF FUNDS (See Instructions)                                        AF

--------------------------------------------------------------------------------
5   CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT            [ ]
TO ITEM 2(d) OR 2(e)                                                     

--------------------------------------------------------------------------------
6   CITIZENSHIP OR PLACE OF ORGANIZATION                         The Netherlands

--------------------------------------------------------------------------------
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:

(7)  SOLE VOTING POWER [0]
(8)  SHARED VOTING POWER [4,030,762]
(9)  SOLE DISPOSITIVE POWER [0]
(10)  SHARED DISPOSITIVE POWER [4,030,762]

--------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,030,762

--------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES                  [ ]
CERTAIN SHARES (See Instructions)                                       

--------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)                    96.6%

--------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON (See Instructions)                              CO

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3

CUSIP NO. 204425 102

--------------------------------------------------------------------------------
1   NAMES OF REPORTING PERSONS                            Tosli Investments N.V.
I.R.S. IDENTIFICATION NOS. OF ABOVE PERSON 
(ENTITIES ONLY):                                                        N/A

--------------------------------------------------------------------------------
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
(See Instructions)
(a) [X]
(b) [ ]
--------------------------------------------------------------------------------
3   SEC USE ONLY

--------------------------------------------------------------------------------
4   SOURCE OF FUNDS (See Instructions)                                       AF

--------------------------------------------------------------------------------
5   CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT           [ ]
TO ITEM 2(d) OR 2(e)                                                     

--------------------------------------------------------------------------------
6   CITIZENSHIP OR PLACE OF ORGANIZATION                         The Netherlands

--------------------------------------------------------------------------------
NUMBER OF SHARE BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:

(7)  SOLE VOTING POWER [0]
(8)  SHARED VOTING POWER [4,030,762]
(9)  SOLE DISPOSITIVE POWER [0]
(10)  SHARED DISPOSITIVE POWER [4,030,762]

--------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,030,762

--------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES                 [ ]
CERTAIN SHARES (See Instructions)                                       

--------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)                    96.6%

--------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON (See Instructions)                              CO

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4

--------------------------------------------------------------------------------
CUSIP NO. 204425 102
--------------------------------------------------------------------------------
1   NAMES OF REPORTING PERSONS                                     Vattenfall AB
I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS 
(ENTITIES ONLY)                                                          N/A

--------------------------------------------------------------------------------
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP                     (a) [X]
(See Instructions)                                                   (b) [ ]

--------------------------------------------------------------------------------
3   SEC USE ONLY

--------------------------------------------------------------------------------
4   SOURCE OF FUNDS (See Instructions)                                       AF

--------------------------------------------------------------------------------
5   CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT            [ ]
TO ITEM 2(d) OR 2(e)                                                     

--------------------------------------------------------------------------------
6   CITIZENSHIP OR PLACE OF ORGANIZATION                                  Sweden

--------------------------------------------------------------------------------
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:

(7)  SOLE VOTING POWER [0]
(8)  SHARED VOTING POWER [4,030,762]
(9)  SOLE DISPOSITIVE POWER [0]
(10)  SHARED DISPOSITIVE POWER [4,030,762]

--------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON     4,030,762

--------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES                 [ ]
CERTAIN SHARES (See Instructions)                                       

--------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)                    96.6%

--------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON (See Instructions)                             CO

--------------------------------------------------------------------------------

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--------------------------------------------------------------------------------
CUSIP NO. 204425 102
--------------------------------------------------------------------------------

1   NAMES OF REPORTING PERSONS                           Nordic Power Invest AB
I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS 
(ENTITIES ONLY)                                                         N/A

--------------------------------------------------------------------------------
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP                     (a) [X]
(See Instructions)                                                   (b) [ ]

--------------------------------------------------------------------------------
3   SEC USE ONLY

--------------------------------------------------------------------------------
4   SOURCE OF FUNDS (See Instructions)                                        AF

--------------------------------------------------------------------------------
5   CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT            [ ]
TO ITEM 2(d) OR 2(e)                                                     

--------------------------------------------------------------------------------
6   CITIZENSHIP OR PLACE OF ORGANIZATION                                  Sweden

--------------------------------------------------------------------------------
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:

(7)  SOLE VOTING POWER [0]
(8)  SHARED VOTING POWER  [4,030,762]
(9)  SOLE DISPOSITIVE POWER [0]
(10)  SHARED DISPOSITIVE POWER [4,030,762]

--------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON     4,030,762

--------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES                  [ ]
CERTAIN SHARES (See Instructions)                                       

--------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)                    96.6%

--------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON (See Instructions)                              CO

--------------------------------------------------------------------------------

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6

--------------------------------------------------------------------------------
CUSIP NO. 204425 102
--------------------------------------------------------------------------------
1   NAMES OF REPORTING PERSONS                                  NRG Energy, Inc.
I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS 
(ENTITIES ONLY)                                                   14-1724239

--------------------------------------------------------------------------------
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP                     (a) [X]
(See Instructions)                                                   (b) [ ]

--------------------------------------------------------------------------------
3   SEC USE ONLY

--------------------------------------------------------------------------------
4   SOURCE OF FUNDS (See Instructions)                                        AF

--------------------------------------------------------------------------------
5   CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT            [ ]
TO ITEM 2(d) OR 2(e)                                                     

--------------------------------------------------------------------------------
6   CITIZENSHIP OR PLACE OF ORGANIZATION                        Delaware, U.S.A.

--------------------------------------------------------------------------------
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:

(7)  SOLE VOTING POWER [0]
(8)  SHARED VOTING POWER [4,030,762]
(9)  SOLE DISPOSITIVE POWER [0]
(10)  SHARED DISPOSITIVE POWER [4,030,762]

--------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON     4,030,762

--------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES                  [ ]
CERTAIN SHARES (See Instructions)                                       

--------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)                    96.6%

--------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON (See Instructions)                             CO

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7

TENDER OFFER

This Rule 13D Amendment relates to the offer by Tosli Acquisition B.V., a
Netherlands private limited liability company (the "Purchaser") and a
wholly-owned subsidiary of Tosli Investments N.V., a Netherlands public limited
liability company ("Tosli") that is equally owned, through subsidiaries, by NRG
Energy, Inc., a Delaware corporation ("NRG") and a wholly-owned subsidiary of
Northern States Power Company, a Minnesota corporation ("NSP"), and Nordic Power
Invest AB, a Swedish corporation ("NPI") and a wholly-owned subsidiary of
Vattenfall AB, a Swedish corporation ("Vattenfall") that is wholly-owned by the
State of Sweden, to purchase all of the outstanding common shares (the
"Shares"), without nominal or par value, of Compania Boliviana de Energia
Electrica S.A. - Bolivian Power Company Limited, a Nova Scotia corporation (the
"Company"), at a purchase price of U.S. $20.00 per Share, net to the seller in
cash, upon the terms and subject to the conditions set forth in the Offer to
Purchase, dated August 26, 1999 (the "Offer to Purchase"), and in the related
Letter of Transmittal (which, as amended from time to time, together constitute
the "Offer"), and the Supplement to the Offer to Purchase, dated October 26,
1999 (the "Supplement"), a copy of which is attached hereto as Exhibit (a)(9).

ITEM 1.  SECURITY AND ISSUER.

The name of the Issuer is Compania Boliviana de Energia Electrica S.A. --
Bolivian Power Company Limited, a Nova Scotia corporation, which has its
principal executive offices at Av. Hernando Siles 5635, Obrajes, La Paz,
Bolivia. The class of equity securities to which this Schedule 13D relates is
the Company's common shares, without nominal or par value. The information set
forth on the cover page and in the "Introduction" of the Offer to Purchase is
incorporated herein by reference.

ITEM 2.  IDENTITY AND BACKGROUND.

(a)-(c), (e) and (f) This Statement is being filed by the Purchaser, Tosli,
NRG, NPI and Vattenfall. The information set forth in Section 7 "THE OFFER -
Certain Information Concerning the Purchaser, Tosli, NRG, NPI, Vattenfall and
NSP" and Schedule A of the Offer to Purchase is incorporated herein by
reference.

(d) During the last five years, neither the Purchaser, Tosli, NRG, NPI nor
Vattenfall, nor, to the best of their knowledge, any of the individuals listed
in Schedule A of the Offer to Purchase has (i) been convicted in a criminal
proceeding (excluding traffic violations or similar misdemeanors) or (ii) been a
party to a civil proceeding of a judicial or administrative body of competent
jurisdiction and, as a result of such proceeding, was or is subject to a
judgment, decree or final order enjoining future violations of, or prohibiting
activities subject to, federal or state securities laws or finding any violation
of such laws.

ITEM 3.  SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION.

The information set forth in the "INTRODUCTION" and Section 8 "THE OFFER -
Source and Amount of Funds" of the Offer to Purchase is incorporated herein by
reference.

ITEM 4.  PURPOSE OF TRANSACTION.

(a)-(e) The information set forth in the "INTRODUCTION," Section 1 "SPECIAL
FACTORS - Background of the Offer; Agreements" and Section 2 "SPECIAL FACTORS -
Purpose of the Offer; Plans for the Company" of the Offer to Purchase is
incorporated herein by reference.

(f)-(j) The information set forth in the "INTRODUCTION" and Section 3
"SPECIAL FACTORS - Effect of the Market for the Shares; Offer on Termination of
Exchange Act Registration" of the Offer to Purchase is incorporated herein by
reference.

ITEM 5.  INTEREST IN SECURITIES OF THE ISSUER.

(a)-(b) The information set forth in the "INTRODUCTION," Section 7 "THE
OFFER - Certain Information Concerning the Purchaser, Tosli, NRG, NPI,
Vattenfall and NSP," Section 1 "SPECIAL FACTORS - Background 

-7-

8

of the Offer; Agreements," Section 2 "SPECIAL FACTORS - Purpose of the Offer;
Plans for the Company," and Schedule A of the Offer to Purchase is incorporated
herein by reference.

(c) Issuer reports no transactions in the class of securities reported on
that were effected during the past sixty days or since the most recent filing of
Schedule 13D.

ITEM 6.  CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT 
TO SECURITIES OF THE ISSUER.

The information set forth in the "INTRODUCTION," Section 7 "THE OFFER -
Certain Information Concerning Purchaser, Tosli, NRG NPI, Vattenfall and NSP,"
Section 8 "THE OFFER - Source and Amount of Funds," Section 1 "SPECIAL FACTORS -
Background of the Offer; Agreements" Section 2 "SPECIAL FACTORS - Purposes of
the Offer; Plans for the Company," and Schedule A of the Offer to Purchase is
incorporated herein by reference.

ITEM 7.  MATERIAL TO BE FILED AS EXHIBITS.

(a)(1)         Offer to Purchase dated August 26, 1999.**

(a)(2)         Form of Letter of Transmittal.**

(a)(3)         Form of Notice of Guaranteed Delivery.**

(a)(4)         Form of Letter to Brokers, Dealers, Commercial Banks, Trust
Companies and other Nominees.**

(a)(5)         Form of Letter to Clients for use by Brokers, Dealers, Commercial
Banks, Trust Companies and other Nominees.**

(a)(6)         Guidelines for Certification of Taxpayer Identification Number on
Substitute Form W-9.**

(a)(7)         Form of Notice of Offer to Purchase.**

(a)(8)         Press Release issued by the Company, dated August 26, 1999.**

(a)(9)         Supplement to Offer to Purchase, dated October 26, 1999.*

(a)(10)        Press Release issued by the Company, dated September 27, 1999.*

(a)(11)        Press Release issued by the Company, dated October 26, 1999.*

(b)            None

(c)(1)         Employment Agreement of Roger J. Dupuis, dated October 7, 1996
(incorporated by reference to the Company's Form 10-K for the
year ended December 31, 1996). **

(c)(2)         Employment Agreement of Roland C. Gibson, dated October 7, 1996
(incorporated by reference to the Company's Form 10-K for the
year ended December 31, 1996).**

(c)(3)         Stockholders Agreement dated as of December 13, 1996, by and
between NRG Energy, Inc. and Nordic Power Invest AB (incorporated
by reference to the Company's Form 8-K dated December 19,
1986).**

(c)(4)         Credit Agreement dated as of August 1, 1997, by and between the
Company and Corporacion Andina de Fomento. (incorporated by
reference to the Company's Form 10-Q for the quarter ended June
30, 1990).**

(c)(5)         Stockholder Maintenance Agreement dated August 1, 1997, by and
among NRG Energy, Inc., Nordic Power Invest AB and Corporation
Andina de Fomento (incorporated by reference to the Company's
Form 10-Q for the quarter ended June 30, 1990).**

(c)(6)         Form of Pledge Agreement dated as of August 1, 1997, by and among
the Company, Corporacion Andina de Fomento and United States
Trust Company of New York (incorporated by reference to the
Company's Form 10-Q for the quarter ended June 30, 1997).**

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9

(c)(7)         Form of Subsidiary Guaranty dated as of August 1, 1997, by and
among the Company, Corporacion Andina de Fomento and all
Restricted Subsidiaries of the Company made a party to the
Agreement by execution of a Joinder to Guaranty in the form
attached thereto (incorporated by reference to the Company's Form
10-Q for the quarter ended June 30, 1997).**

(c)(8)         Form of Indenture dated as of August 1, 1997, by and between the
Company and Corporacion Andina de Fomento (incorporated by
reference to the Company's Form 10-Q for the quarter ended June
30, 1997).**

(c)(9)         Development Services Agreement, dated October 9, 1998, between
Cobee Development LLC and the Company (incorporated by reference
to the Company's Form 10-K for the year ended December 31,
1998).**

(d)            None

(e)            Not applicable.

(f)            Not applicable.

*        Filed herewith.
**       Previously filed.

-9-

10

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this statement is true, complete and correct.

Dated: October 26, 1999                Tosli Acquisition B.V.

By: /s/ Valorie A. Knudsen               
--------------------------------------
Valorie A. Knudsen
Director of Tosli Investments N.V.

And By: /s/ Gunnar Vallin               
----------------------------------
Gunnar Vallin
Director of Tosli Investments N.V.

Tosli Investments N.V.

By: /s/ Valorie A. Knudsen               
--------------------------------------
Valorie A. Knudsen
Director

And By: /s/ Gunnar Vallin                
----------------------------------
Gunnar Vallin
Director

NRG Energy, Inc.

By: /s/ Valorie A. Knudsen               
--------------------------------------
Valorie A. Knudsen
Vice President, Corporate Strategy and
Emerging Markets

Nordic Power Invest AB

By: /s/ Gunnar Vallin                   
--------------------------------------
Gunnar Vallin
President
Vattenfall AB

By: /s/ Gunnar Vallin                   
--------------------------------------
Gunnar Vallin
President of Nordic Power Invest AB

-10-

11

EXHIBIT INDEX

(a)(1)         Offer to Purchase dated August 26, 1999.**

(a)(2)         Form of Letter of Transmittal.**

(a)(3)         Form of Notice of Guaranteed Delivery.**

(a)(4)         Form of Letter to Brokers, Dealers, Commercial Banks, Trust
Companies and other Nominees.**

(a)(5)         Form of Letter to Clients for use by Brokers, Dealers, Commercial
Banks, Trust Companies and other Nominees.**

(a)(6)         Guidelines for Certification of Taxpayer Identification Number on
Substitute Form W-9.**

(a)(7)         Form of Notice of Offer to Purchase.**

(a)(8)         Press Release issued by the Company, dated August 26, 1999.**

(a)(9)         Supplement to Offer to Purchase, dated October 26, 1999.*

(a)(10)        Press Release issued by the Company, dated September 27, 1999.*

(a)(11)        Press Release issued by the Company, dated October 26, 1999.*

(b)            None

(c)(1)         Employment Agreement of Roger J. Dupuis, dated October 7, 1996
(incorporated by reference to the Company's Form 10-K for the
year ended December 31, 1996). **

(c)(2)         Employment Agreement of Roland C. Gibson, dated October 7, 1996
(incorporated by reference to the Company's Form 10-K for the
year ended December 31, 1996).**

(c)(3)         Stockholders Agreement dated as of December 13, 1996, by and
between NRG Energy, Inc. and Nordic Power Invest AB (incorporated
by reference to the Company's Form 8-K dated December 19,
1986).**

(c)(4)         Credit Agreement dated as of August 1, 1997, by and between the
Company and Corporacion Andina de Fomento. (incorporated by
reference to the Company's Form 10-Q for the quarter ended June
30, 1990).**

(c)(5)         Stockholder Maintenance Agreement dated August 1, 1997, by and
among NRG Energy, Inc., Nordic Power Invest AB and Corporation
Andina de Fomento (incorporated by reference to the Company's
Form 10-Q for the quarter ended June 30, 1990).**

(c)(6)         Form of Pledge Agreement dated as of August 1, 1997, by and among
the Company, Corporacion Andina de Fomento and United States
Trust Company of New York (incorporated by reference to the
Company's Form 10-Q for the quarter ended June 30, 1997).**

(c)(7)         Form of Subsidiary Guaranty dated as of August 1, 1997, by and
among the Company, Corporacion Andina de Fomento and all
Restricted Subsidiaries of the Company made a party to the
Agreement by execution of a Joinder to Guaranty in the form
attached thereto (incorporated by reference to the Company's Form
10-Q for the quarter ended June 30, 1997).**

(c)(8)         Form of Indenture dated as of August 1, 1997, by and between the
Company and Corporacion Andina de Fomento (incorporated by
reference to the Company's Form 10-Q for the quarter ended June
30, 1997).**

(c)(9)         Development Services Agreement, dated October 9, 1998, between
Cobee Development LLC and the Company (incorporated by reference
to the Company's Form 10-K for the year ended December 31,
1998).**

(d)            None

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(e)            Not applicable.

(f)            Not applicable. 
*          Filed herewith. 
**         Previously filed.

-12-

1

SUPPLEMENT TO OFFER TO PURCHASE FOR CASH
ALL OUTSTANDING COMMON SHARES OF

COMPANIA BOLIVIANA DE ENERGIA ELECTRICA S.A. --
BOLIVIAN POWER COMPANY LIMITED
AT

U.S. $20.00 NET PER SHARE
BY

TOSLI ACQUISITION B.V.
A WHOLLY-OWNED SUBSIDIARY OF

TOSLI INVESTMENTS N.V.
THE PRINCIPAL SHAREHOLDER OF THE COMPANY

THE OFFER AND WITHDRAWAL RIGHTS HAS BEEN EXTENDED SUCH THAT THE OFFER WILL
EXPIRE AT 12:00 MIDNIGHT, NEW YORK CITY TIME, ON NOVEMBER 8, 1999, UNLESS THE
OFFER IS FURTHER EXTENDED.

THIS SUPPLEMENT, DATED OCTOBER 26, 1999, SUPPLEMENTS AND AMENDS THE OFFER
TO PURCHASE, DATED AUGUST 26, 1999, RELATING TO THE PROPOSED OFFER TO PURCHASE
FOR CASH ALL OUTSTANDING COMMON SHARES, WITHOUT NOMINAL OR PAR VALUE, OF
COMPANIA BOLIVIANA DE ENERGIA ELECTRICA S.A. -- BOLIVIAN POWER COMPANY LIMITED,
A NOVA SCOTIA CORPORATION (THE "COMPANY"), FOR A CASH PRICE OF U.S. $20.00 NET
PER SHARE. THIS SUPPLEMENT, WHICH SHOULD BE READ IN CONJUNCTION WITH THE OFFER
TO PURCHASE, IS BEING PROVIDED TO GIVE YOU CERTAIN ADDITIONAL INFORMATION. THE
MATERIAL TERMS OF THE OFFER HAVE NOT BEEN CHANGED, OTHER THAN TO EXTEND THE DATE
FOR TENDERING YOUR SHARES FROM OCTOBER 25, 1999 TO NOVEMBER 8, 1999. YOU MAY
CONTINUE TO USE THE LETTER OF TRANSMITTAL AND PROCEDURES FOR TENDERING
PREVIOUSLY DELIVERED TO YOU. CAPITALIZED TERMS USED HEREIN AND NOT OTHERWISE
DEFINED HAVE THE MEANINGS ASCRIBED TO THEM IN THE OFFER TO PURCHASE.

-------------------------

IMPORTANT

QUESTIONS OR REQUESTS FOR ASSISTANCE MAY BE DIRECTED TO THE INFORMATION
AGENT AT THE ADDRESS AND TELEPHONE NUMBERS SET FORTH ON THE BACK COVER OF THIS
SUPPLEMENT. ADDITIONAL COPIES OF THIS SUPPLEMENT, THE OFFER TO PURCHASE, THE
LETTER OF TRANSMITTAL AND THE NOTICE OF GUARANTEED DELIVERY MAY ALSO BE OBTAINED
FROM THE INFORMATION AGENT OR BROKERS, DEALERS, COMMERCIAL BANKS OR TRUST
COMPANIES.

-------------------------

October 26, 1999

2

TO THE HOLDERS OF COMMON SHARES OF
COMPANIA BOLIVIANA DE ENERGIA ELECTRICA S.A. -- BOLIVIAN POWER COMPANY LIMITED:

The Offer to Purchase is amended and supplemented as follows:

1. The captions in the Offer to Purchase were rearranged as follows:

INTRODUCTION

SPECIAL FACTORS

1. Background of the Offer; Agreements

2. Purposes of the Offer; Plans for the Company

3. Effect of the Offer on the Market for the Shares; Termination of Exchange
Act Registration

4. Certain Income Tax Consequences of the Offer

THE OFFER

1. Terms of the Offer, Expiration Date

2. Acceptance for Payment and Payment

3. Procedure for Tendering Shares

4. Withdrawal Rights; Possible Purchase of Shares Not Tendered

5. Price Range of Shares; Dividends

6. Certain Information Concerning the Company

7. Certain Information Concerning the Purchaser, Tosli, NRG, NPI, Vattenfall
and NSP

8. Source and Amounts of Funds

9. Certain Conditions to the Offer

10. Certain Legal Matters; Regulatory Approvals

11. Fees and Expenses

12. Miscellaneous

Schedule A

2. The first paragraph under "SPECIAL FACTORS -- 1. Background of the
Offer; Agreements -- Background of the Offer" is hereby amended to insert the
following sentence at the end thereof:

"The alternatives considered included (i) a short-form merger or
consolidation and (ii) an issuer tender offer. After assessing the various
alternatives, the Company determined that the going private transaction was
superior to the other alternatives in terms of providing the Stockholders
with liquidity. Specifically, the first option would force the Stockholders
to exchange their Shares without providing them with any other options and
would require that the Company reincorporate in the state of Delaware which
would in turn jeopardize the Company's Bolivian concession. The second
option would have prevented Tosli from acquiring the remaining shares under
Nova Scotia law."

3. Following the third paragraph under "SPECIAL FACTORS -- 1. Background of
the Offer; Agreements -- Background of the Offer" we have added the following
new paragraphs:

"After discussion by the full Board, all but two of whose members are
representatives of NPI and NRG (see Schedule A), the Members of the Board
decided to defer a determination of the fairness of a U.S. $20.00 Offer
Price pending review of additional information concerning the current value
of the Company's Shares. Thereafter certain representatives of NRG serving
as Members of the Board obtained

3

and reviewed additional information relating to the implied market value of
the Company's Shares based on actual and forecasted results, current market
comparables and current economic factors. This information was then
presented to the other Board Members.

The additional information reviewed included (i) certain information
relating to the business, financial condition and operations of the
Company; (ii) certain internal financial planning information of the
Company; (iii) certain financial and other securities data relating to the
Company and other publicly traded South American utility companies deemed
similar to the Company or representative of the business sector in which
the Company operates, consisting of: Endesa Chile, Gener, Central Puerto
and Costanera (the "Selected Companies").

As part of the analysis various financial multiples and ratios based
on published stock prices for each of the Selected Companies were
calculated and compared. The following were factors considered with respect
to the Selected Companies based on year-to-date earnings:

- the ratio of firm value to earnings before interest, taxes,
depreciation and amortization ratios, where firm value equals
equity value plus straight debt, minority interest, straight
preferred stock, all out-of-money convertibles, less investments
in unconsolidated affiliates and cash, which ranged from 3.2x to
11.3x;

- the ratio of equity market value to net income, which ranged from
0.0 to 12.1x;

- the ratio of equity market value to book value, which ranged from
0.6x to 1.2x;

- the ratio of equity value to megawatt hours of electricity sold,
which ranged from $54 to $499; and

- the ratio of equity value to generating capacity, which ranged
from $348 to $1,868.

These calculations yielded an implied value of the Company's Shares in
the range of $11.50 to $19.50, with a mid-point of $16.00 per share.

The information relied on for these calculations was not independently
reviewed by the Board for accuracy and was relied on as being complete in all
respects. In the analysis provided to the Board as to the implied value of the
Company's Shares, no single analysis or factor was relied upon nor were relative
weights assigned to the analysis or factors used. Accordingly, an analysis of
the results is not mathematical; rather, it involves complex considerations and
judgments concerning differences in the various characteristics of the Selected
Companies and other factors that could affect the nature of the comparisons of
the Selected Companies to which the Company was compared."

4. Following the fourth paragraph under "SPECIAL FACTORS -- 1. Background
of the Offer; Agreements -- Background of the Offer" we have added the following
new paragraphs:

"The Offer was determined to be procedurally fair because, among other
things:

(i)   the Board has two directors who are not affiliates of NRG or NPI,
shareholders of Tosli;

(ii)  the Board reviewed the business and financial condition of the
Company; and

(iii) the deliberations pursuant to which the Board evaluated the
Offer.

FORWARD-LOOKING INFORMATION

Certain information included in this Offer contains statements that are
forward-looking. Such forward-looking information involves risks and
uncertainties that could significantly affect anticipated results in the future
and, accordingly, such results may differ from those expressed in any
forward-looking statements made by or on behalf of the Company."

4

5. The first paragraph under "THE OFFER -- 4. Withdrawal Rights; Possible
Purchase of Shares Not Tendered -- Possible Purchase of Shares Not Tendered" is
hereby replaced in its entirety by inserting the following in lieu thereof:

"The Companies Act of the Province of Nova Scotia, under which the
Company was incorporated, provides in substance (in Section 132) that if,
at the conclusion of a tender offer for all of the outstanding securities
of a company (the "Transferor Company") that has been held open for tenders
for a period of at least four months, tenders are received and accepted for
at least 90% of the Transferor Company's outstanding shares, the party
acquiring shares in the tender offer (the "Transferee Company") may, within
four months after the termination of the tender offer, give notice to
non-tendering holders of shares, that it desires to purchase all of such
shares for the same per-share consideration paid in the tender offer. If
such notice is given by the Transferee Company, unless upon application by
a non-tendering shareholder to a court of competent jurisdiction stating
that the Transferee Company is not entitled to the benefits of Section 132
and, within one month following such notice such court orders otherwise,
the Transferee Company will have the right and become bound to acquire the
shares not tendered for that consideration. At the end of the one-month
period (or such later date as a court to whom application has been made
makes its final determination), the Transferee Company must transfer to the
Transferor Company the funds necessary to purchase the shares not tendered,
to be held in trust for the benefit of the holders of such shares. Upon the
transfer of such funds, the Transferee Company will become the holder of
record of such shares. Apart from the application process described herein,
non-tendering shareholders do not possess any other rights, including
dissenters rights."

Dated: October 26, 1999                 Tosli Acquisition B.V.

By:      /s/ VALORIE A. KNUDSEN
-------------------------------------
Valorie A. Knudsen
Director of Tosli Investments N.V.

And By:     /s/ GUNNAR VALLIN
-----------------------------------
Gunnar Vallin
Director of Tosli Investments N.V.

5

THE DEPOSITARY FOR THE OFFER IS:

U.S. BANK TRUST NATIONAL ASSOCIATION

By Hand:                                By Mail or Overnight Courier:
U.S. Bank Trust National Association               U.S. Bank Trust National Association
Attention: Corporate Trust Department                      U.S. Bank Trust Center
100 Wall Street -- 20th Floor                Attention: Specialized Finance Department
New York, New York 10005                       180 East Fifth Street, Suite 200
St. Paul, Minnesota 55101

By Facsimile Transmission:
(For Eligible Institutions Only)
Telecopier Number: (651) 244-1537

Confirm Receipt of Facsimile by Telephone Only:
Telephone Number: (651) 244-5172

Any questions or requests for assistance or additional copies of this Offer
to Purchase, the Letter of Transmittal and the Notice of Guaranteed Delivery may
be directed to the Information Agent at its telephone number and location listed
below. You may also contact your broker, dealer, commercial bank or trust
company or nominee for assistance concerning the Offer.

The Information Agent for the Offer is:

MACKENZIE PARTNERS, INC.
156 5th Avenue
New York, New York 10010

Banks and Brokers Call Collect: (212) 929-5500
All Others Call Toll Free: (800) 322-2885

1

PRESS RELEASE                                                 SEPTEMBER 27, 1999

TOSLI ACQUISITION B.V. EXTENDS TENDER OFFER FOR COMPANIA BOLIVIANA DE ENERGIA
ELECTRICA S.A. - BOLIVIAN POWER COMPANY LIMITED'S STOCK TO OCTOBER 25, 1999

New York, New York - September 27, 1999. Today, Compania Boliviana de Energia
Electrica S.A. - Bolivian Power Company Limited (the "Company") announced that
the tender offer of Tosli Acquisition B.V. ("Tosli") for all outstanding shares
of the Company's common stock has been extended until 12:00 Midnight, New York
City time, on Monday, October 25, 1999.

According to Tosli and the Company, the tender offer has been extended to
provide the shareholders additional time to tender their shares. In addition,
supplemental information will be promptly forwarded to the shareholders of the
Company when it becomes available.

Tosli's tender offer was scheduled to expire at Midnight, New York City time, on
Friday, September 24, 1999. According to the Company's Form 10-Q for the period
ended June 30, 1999, as of August 11, 1999, 4,202,575 shares were issued and
outstanding, and 9,700 shares were reserved for issuance pursuant to employee
stock options. The Depositary for the offer, U.S. Bank Trust National
Association, has advised Tosli that 38,670 outstanding shares of the Company
have been tendered as of the close of business on Thursday, September 23, 1999.

For more information, reporters may contact the Information Agent:

MACKENZIE PARTNERS, INC.
156 5th Avenue
New York, New York 10010
(800) 322-2885

1
PRESS RELEASE                                                 OCTOBER 26, 1999

TOSLI ACQUISITION B.V. EXTENDS TENDER OFFER FOR COMPANIA BOLIVIANA de ENERGIA
ELECTRICA S.A. - BOLIVIAN POWER COMPANY
LIMITED'S STOCK TO NOVEMBER 8, 1999

New York, New York -October 26, 1999. Today, Compania Boliviana de Energia
Electrica S.A. - Bolivian Power Company Limited (the "Company") announced that
the tender offer of Tosli Acquisition B.V. ("Tosli") for all outstanding shares
of the Company's common stock has been extended until 12:00 Midnight, New York
City time, on Monday, November 8, 1999.

Tosli's tender offer was scheduled to expire at Midnight, New York City time, on
Monday, October 25, 1999. The Depositary for the offer, U.S. Bank Trust National
Association, has advised Tosli that 82,505 outstanding shares of the Company
have been tendered as of the close of business on Friday, October 22, 1999.

For more information, reporters may contact the Information Agent:

MACKENZIE PARTNERS, INC.
156 5th Avenue
New York, New York 10010
(800) 322-2885