<PAGE>   1

                                    FORM 10-K
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


[X]  ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE
     ACT OF 1934

For the fiscal year ended December 31, 1999

Commission File number 33-51630:

                     CHIEFTAIN INTERNATIONAL FUNDING CORP.
             (Exact name of registrant as specified in its charter)

          NEVADA                                      98-0127391
(State or other jurisdiction of          (I.R.S. Employer Identification No.)
 incorporation or organization)

   1201 TD TOWER, 10088 - 102 AVENUE,                 T5J 2Z1
       EDMONTON, ALBERTA, CANADA                   (Postal code)
       (Address of Registrant's
     principal executive offices)

Registrant's telephone number, including area code: (780) 425-1950

SECURITIES REGISTERED PURSUANT TO SECTION 12(b) OF THE ACT:

<TABLE>
<CAPTION>
Title of each class                                              Name of each exchange on which registered
<S>                                                              <C>

$1.8125 Convertible Redeemable Preferred Stock                   American Stock Exchange
</TABLE>

SECURITIES REGISTERED PURSUANT TO SECTION 12(g) OF THE ACT:      NONE

Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months (or for such shorter period that the registrant was
required to file such reports), and (2) has been subject to such filing
requirements for the past 90 days. Yes [X] No [ ]

This report contains forward-looking statements that are subject to risk factors
associated with the oil and gas business. The Company believes that the
expectations reflected in these statements are reasonable, but may be affected
by a variety of factors including, but not limited to: price fluctuations,
currency fluctuations, drilling and production results, imprecision of reserve
estimates, loss of market, industry competition, environmental risks, political
risks and capital restrictions.

<PAGE>   2

                      CHIEFTAIN INTERNATIONAL FUNDING CORP.
                          1999 FORM 10-K ANNUAL REPORT

                                Table of Contents

                                     PART I

<TABLE>
<CAPTION>
                                                                                                      Page
<S>                                                                                                   <C>
     Item 1.  Business .........................................................................       1
              Employees ........................................................................       1
     Item 2.  Properties .......................................................................       1
     Item 3.  Legal Proceedings ................................................................       1
     Item 4.  Submission of Matters to a Vote of Security Holders ..............................       1
</TABLE>
                                    PART II
<TABLE>
<S>                                                                                                   <C>
     Item 5.  Market for the Registrant's Securities and Related Stockholder Matters ...........       2
     Item 6.  Selected Financial Data ..........................................................       3
     Item 7.  Management's Discussion and Analysis of Financial Condition and
                Results of Operations ..........................................................       3
     Item 8.  Financial Statements and Supplementary Data ......................................       4
     Item 9.  Changes in and Disagreements with Accountants on Accounting and
                Financial Disclosure ...........................................................       4
</TABLE>
                                    PART III
<TABLE>
<S>                                                                                                   <C>
     Item 10. Directors and Executive Officers .................................................       4
     Item 11. Executive Compensation ...........................................................       6
     Item 12. Security Ownership of Certain Beneficial Owners and Management ...................       6
     Item 13. Certain Relationships and Related Transactions ...................................       7
</TABLE>
                                    PART IV
<TABLE>
<S>                                                                                                   <C>
     Item 14. Exhibits and Reports on Form 8-K .................................................       7

Signatures .....................................................................................      14
</TABLE>



<PAGE>   3

                                     PART I

ITEM 1. BUSINESS

Chieftain International Funding Corp. ("Funding Corp." or the "Company") is a
Nevada subsidiary of Chieftain International (U.S.) Inc. ("Chieftain U.S."), a
Nevada corporation which is, in turn, a wholly-owned subsidiary of Chieftain
International, Inc., an Alberta, Canada corporation. The primary purpose of
Funding Corp. is to finance business operations of Chieftain U.S.

On each of August 28, 1992 and November 5, 1992, Funding Corp. issued 100,000
common shares to Chieftain U.S. for total cash proceeds of $15.0 million.

Funding Corp. commenced operations on November 6, 1992 with the initial public
offering of 2,400,000 $1.8125 Convertible Redeemable Preferred Shares
("Preferred Shares"). An additional 326,700 Preferred Shares were issued
pursuant to the underwriter's exercise of an over-allotment option. Proceeds of
the issuance of Preferred Shares, net of offering costs of $4.7 million, were
$63.4 million. The Preferred Shares are redeemable at the option of the Company
at $25.4028 per share during 2000, $25.2014 per share during 2001 and $25.00 per
share after December 31, 2001, plus accumulated and unpaid dividends. Each
preferred share is convertible at any time at the option of the holder into 1.25
common shares of Chieftain International, Inc. (the ultimate parent company).
Dividends on the Preferred Shares are paid quarterly at the annual rate of
$1.8125 per share.

On November 6, 1992, Funding Corp. purchased 2,840,000 $1.8125 Redeemable Class
B Preferred Shares of Chieftain U.S., its parent company, at $25.00 per share,
and subsequently purchased an additional 300,000 of such shares to hold a total
of 3,140,000 such shares. Funding Corp. receives quarterly dividends on such
shares at the annual rate of $1.8125 per share. The shares are redeemable at the
option of the issuer at $25.4028 per share during 2000, $25.2014 per share
during 2001 and $25.00 after December 31, 2001, plus accumulated and unpaid
dividends.

Since December 31, 1992, Funding Corp. has, from time to time, purchased
short-term notes, payable by Chieftain U.S., with funds in excess of working
capital requirements. Such notes bear interest at competitive money market
rates.

Chieftain U.S. is engaged in the acquisition of gas and oil reserves through
purchase and through exploration and development and in gas and oil production
and sales in the United States. Its principal properties are located in the U.S.
federal waters of the Gulf of Mexico and onshore in southeast Utah and
Louisiana. Reference is made to the information describing United States
properties and operations in the Form 10-K Annual Report of Chieftain
International, Inc. for the year ended December 31, 1999, which is attached as
Exhibit 28 hereto. Chieftain International, Inc. has guaranteed dividend,
conversion and redemption obligations of Funding Corp. with respect to the
Preferred Shares.

EMPLOYEES

At December 31, 1999, Funding Corp. had no employees. Management services are
provided by Chieftain International, Inc.

ITEM 2. PROPERTIES

Funding Corp. owns no physical properties. Its assets consist of investments in
and advances to Chieftain U.S., its parent company.

ITEM 3. LEGAL PROCEEDINGS

Funding Corp. is not a party to any material legal proceeding.

ITEM 4. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS

No matters were submitted to a vote of security holders of the Company during
the fourth quarter of 1999.



                                       1
<PAGE>   4

                                       PART II

ITEM 5. MARKET FOR THE REGISTRANT'S SECURITIES AND RELATED STOCKHOLDER MATTERS

The high and low prices of the Chieftain International Funding Corp. $1.8125
Convertible Redeemable Preferred Shares (the "Preferred Shares") during each
quarter since December 31, 1997 are shown below.

Price History of Chieftain International Funding Corp. $1.8125
Convertible Redeemable Preferred Shares on the American Stock Exchange

<TABLE>
<CAPTION>
                             High          Low
                             ----          ---
                                 (US dollars)
<S>                       <C>          <C>
1998
   First quarter ........ $   32.00    $   26.75
   Second quarter .......     32.50        27.75
   Third quarter ........     30.87        22.75
   Fourth quarter .......     28.88        23.00

1999
   First quarter ........     25.25        20.25
   Second quarter .......     27.25        23.25
   Third quarter ........     29.88        26.00
   Fourth quarter .......     28.06        23.13

2000
   January ..............     25.50        24.13
   February .............     25.25        21.75
   March 1 to March 14 ..     24.75        22.00
</TABLE>

All of the Company's issued common shares are owned by its parent, Chieftain
International (U.S.) Inc. The Preferred Shares were held by 49 shareholders of
record on December 31, 1999.

The Company has made timely payment of quarterly dividends on the Preferred
Shares, amounting to $0.453125 per share, for each quarter since the shares were
issued in 1992.



                                       2
<PAGE>   5

ITEM 6. SELECTED FINANCIAL DATA

The selected financial data for each of the five years in the period ended
December 31, 1999 has been derived from the financial statements of Funding
Corp. and should be read in conjunction with such financial statements and the
related notes.


                      Chieftain International Funding Corp.

<TABLE>
<CAPTION>
YEAR ENDED DECEMBER 31,                         1999        1998       1997        1996        1995
-----------------------                         ----        ----       ----        ----        ----
                                                 (in thousands except shares and per share amounts)
<S>                                           <C>        <C>         <C>         <C>         <C>
INCOME STATEMENT DATA:
Revenue ...................................   $  5,914   $  5,897    $  5,867    $  5,826    $  5,792
General and administrative expenses .......         70        176          77          46          44
Income before dividends on preferred shares      5,790      5,710       5,755       5,748       5,748
Dividends on preferred shares .............      4,942      4,942       4,942       4,942       4,942
Net income applicable to common shares ....        848        768         813         806         806
Net income per common share ...............       4.24       3.84        4.07        4.03        4.03
Number of common shares outstanding .......    200,000    200,000     200,000     200,000     200,000

OTHER DATA:
Cash provided from operating activities ...   $    847   $    768    $    815    $    993    $    617

BALANCE SHEET DATA (at end of period):
Working capital ...........................   $  5,535   $  4,687    $  3,920    $  3,106    $  2,300
Total assets ..............................   $ 84,041   $ 83,194    $ 82,425    $ 81,610    $ 82,040
Preferred shares issued ...................   $ 63,403   $ 63,403    $ 63,403    $ 63,403    $ 63,403
Common shareholder's equity ...............   $ 20,633   $ 19,785    $ 19,017    $ 18,203    $ 17,398
</TABLE>



ITEM 7. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
OF OPERATIONS

Funding Corp., a special purpose subsidiary of Chieftain International (U.S.)
Inc., was formed in 1992 for the primary purpose of financing the US business
operations of its parent.

ANALYSIS OF OPERATING RESULTS

Funding Corp.'s income is derived from dividends on preferred shares and
interest on short-term notes, all of which are issued by its parent company,
Chieftain International (U.S.) Inc.

Dividends received on 3,140,000 redeemable Class B preferred shares amounted to
$5,691,250 in each of the years 1999, 1998 and 1997. In addition to such
dividend income, interest of $222,978, $205,865 and $175,599 in 1999, 1998 and
1997, respectively, was earned on short-term investments.

Dividend income is expected to remain the same for 2000 while interest income is
expected to increase, assuming stable interest rates, reflecting the larger
amount of short-term investments held.

General and administrative expenses decreased significantly in 1999 due to
non-recurring professional fees incurred in 1998 in respect of regulatory
matters.

Income taxes are calculated on interest income less general and administrative
costs. Dividends received from the parent are tax exempt.

Dividends in the amount of $4,942,144 were paid in 1999, unchanged from 1998 and
1997.




                                       3
<PAGE>   6

CAPITAL RESOURCES AND LIQUIDITY

Funding Corp. is dependent upon the dividend income from its investment in
preferred shares of its parent company to provide funds for payment of dividends
on its publicly-held preferred shares.

Funds provided from operations decreased to $846,961 in 1999 compared to
$768,418 in 1998 and $815,049 in 1997. Most of these funds were invested in
short-term notes issued and payable by the parent company. Cash balances at
December 31, 1999 and 1998 were $147,982 and $121,495 respectively.

YEAR 2000

The Year 2000 issue arose because many computerized systems used two digits
rather than four to identify a year. Date-sensitive systems may recognize the
year 2000 as 1900 or some other date, resulting in errors when information using
year 2000 dates is processed. In addition, similar problems may have arisen in
some systems which used certain dates in 1999 to represent something other than
the date. Although the change in date has occurred, it is not possible to
conclude that all aspects of the Year 2000 Issue that may affect Funding Corp.,
including those related to suppliers or other third parties, have been fully
resolved. No Year 2000 Issue related event has occurred that materially affects
Funding Corp.

ITEM 8. FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

The following financial statements of Chieftain International Funding Corp. are
included in Part IV of this report.

     Auditors' Report

     Balance Sheet as at December 31, 1999 and 1998

     Statement of Income and Retained Earnings for the years ended December 31,
     1999, 1998 and 1997

     Statement of Cash Flows for the years ended December 31, 1999, 1998 and
     1997

     Notes to Financial Statements

ITEM 9. CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND
FINANCIAL DISCLOSURE

There have been no disagreements between Funding Corp. and Funding Corp.'s
auditors on accounting or financial disclosure matters.

                                    PART III

ITEM 10. DIRECTORS AND EXECUTIVE OFFICERS

The Board of Directors of the Company consists of not less than three nor more
than ten directors. The number of directors within these limits is fixed from
time to time by resolution of the Board of Directors and is currently eight.
Directors are elected annually by the common stockholder to hold office until
the close of the next ensuing annual meeting.

Information is presented below with respect to the directors of the Company. The
information includes age as of the date hereof, present position with the
Company and other business experience during the past five years. Except as
noted, all of the directors of the Company have served as such since the
Company's formation in November, 1992 and all are also directors of Chieftain
International (U.S.) Inc., the immediate parent of the Company and Chieftain
International, Inc., the ultimate parent of the Company. S.C. Hurley became a
director of each of such companies in 1997. Also presented is information with
respect to directors' ownership of securities of the Company and its ultimate
parent, and the ownership of such securities by the directors and executive
officers as a group. A director need not be a shareholder of the Company.



                                       4
<PAGE>   7


<TABLE>
<CAPTION>
                                                                 Shares Beneficially Owned and Percent of Class (1)
                                                                               as at February 29, 2000
                                                                 --------------------------------------------------
                                                                   Common Shares                    Preferred Shares
                                                                         of                                of
                                                             Chieftain International,Inc.          Chieftain Funding (2)
                                                             ----------------------------          ---------------------
<S>                                                          <C>                  <C>               <C>            <C>
STEPHEN C. HURLEY, 50, Director.
Senior Vice President and Chief Operating Officer of
Chieftain International, Inc.                                   107,221(3)            --                  --           --

HUGH J. KELLY, 74, Director.
Corporate Director and
Energy Consultant.(4)                                            37,666(5)            --              10,000           --

JOHN E. MAYBIN, 75, Director.
Corporate Director.                                              37,666(6)            --                  --           --

STANLEY A. MILNER, A.O.E., LL.D., 71, Director.
President and Chief Executive Officer of
Chieftain International, Inc.(7)                                676,991(8)           4.1%             39,000          1.4%

DAVID E. MITCHELL, O.C., 73,
Chairman of the Board.
Chairman Emeritus, Alberta Energy Company Ltd.                   46,666(5)            --                  --           --

LOUIS G. MUNIN, 66, Director.
Corporate Director and
Financial Consultant (9)                                         40,666(5)            --               2,000           --

ESTHER S. ONDRACK, 59, Director.
Senior Vice President and Secretary of
Chieftain International, Inc.                                   100,110(10)           --                  --           --

STUART T. PEELER, 70, Director.
Corporate Director and
Petroleum Industry Consultant.(11)                               19,466(12)           --              30,000          1.1%

DIRECTORS AND EXECUTIVE
OFFICERS AS A GROUP                                           1,206,243(13)          7.2%             81,000          3.0%
</TABLE>

     (1)  Percentages of less than one are omitted.
     (2)  Each $1.8125 Convertible Redeemable Preferred Share of Chieftain
          International Funding Corp. is convertible into 1.25 common shares of
          Chieftain International, Inc.
     (3)  Includes options, exercisable within 60 days, to purchase 103,331
          shares.
     (4)  H.J. Kelly is a director of Gulf Island Fabrication Inc. and
          Tidewater Inc.
     (5)  Includes options, exercisable within 60 days, to purchase 36,666
          shares.
     (6)  Includes options, exercisable within 60 days, to purchase 36,166
          shares.
     (7)  S.A. Milner is a director of Alberta Energy Company Ltd.
     (8)  Includes options, exercisable within 60 days, to purchase 128,332
          shares. In addition, an associate of S.A. Milner owns 3,000 shares.
     (9)  L.G. Munin is a director of Lafarge Canada Inc. and Walden Residential
          Properties, Inc.
     (10) Includes options, exercisable within 60 days, to purchase 77,498
          shares.
     (11) S.T. Peeler is a director of Homestake Mining Company.
     (12) Options exercisable within 60 days.
     (13) Includes options, exercisable within 60 days, to purchase 563,960
          shares.



                                       5
<PAGE>   8

EXECUTIVE OFFICERS

The following table lists the name and age of each Executive Officer and all
positions and offices with the Company held by each such person. The officers
are appointed each year at the directors' meeting immediately following the
annual meeting of the shareholder. The next such meeting will be held on May 25,
2000.



<TABLE>
<CAPTION>
NAME                      AGE        POSITION/OFFICE
----                      ---        ---------------
<S>                       <C>        <C>
S.A.Milner                71         Director, President and Chief Executive Officer
S.C.Hurley                50         Director, Senior Vice President and Chief Operating Officer
E.S.Ondrack               59         Director, Senior Vice President and Secretary
S.J.Milner                42         Vice President, Drilling and Production
R.J.Stefure               52         Vice President and Controller
R.P. Boyd                 43         Vice President, Investor Relations
</TABLE>


With the following exceptions all of the officers have held positions as
officers of the Company since its incorporation in 1992 and each officer
presently holds and has held for more than five years positions as officers of
Chieftain International, Inc. and Chieftain International (U.S.) Inc., the
former, in each case, being his or her principal occupation. S.C. Hurley joined
Chieftain in September, 1995 prior to which time he was the Vice President
Exploration of a U.S. based integrated oil company. S.J. Milner and R.J. Stefure
were appointed officers of the Company in June, 1995 and prior thereto held
management positions with the Company and its immediate and ultimate parents.
R.P. Boyd joined the Company in 1999 prior to which time he was Chief Financial
Officer and Controller of a Canadian independent oil and gas company.

There are no family relationships among the executive officers and directors
except between S.A. Milner and D.E. Mitchell who are first cousins and between
S.A. Milner and S.J. Milner who are father and son.

ITEM 11. EXECUTIVE COMPENSATION

The directors and officers, including the chief executive officer, receive no
compensation in their capacities as directors and officers of Funding Corp. All
of the officers are employees of and receive remuneration from Chieftain
International, Inc.

ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

The following table shows the share ownership in the voting securities of the
Company of each person or company beneficially owning, or exercising control or
direction over, more than five per cent of the outstanding shares of the
Company.

<TABLE>
<CAPTION>
                                                                Class           Number of shares           Percent of
Name and address of beneficial owner                           of shares        beneficially owned         class owned
------------------------------------                           ---------        ------------------         -----------
<S>                                                            <C>              <C>                        <C>
Chieftain International (U.S.) Inc.
1201 TD Tower, 10088 - 102 Avenue
Edmonton, Alberta, Canada
T5J 2Z1                                                         Common               200,000                   100%
</TABLE>



Information with respect to shares beneficially owned in the registrant and its
ultimate parent, Chieftain International, Inc., by directors and executive
officers of the Company, is presented in Item 10, "Directors and Executive
Officers".



                                       6
<PAGE>   9

ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

Under the terms of an informal understanding between the Company and Chieftain
International, Inc. ("Chieftain Canada"), Chieftain Canada provides management
services as required to enable the Company to carry on its business.

Chieftain Canada has unconditionally guaranteed certain obligations of the
Company with respect to the Preferred Shares. The Preferred Shares are
redeemable, at the option of the Company, at $25.4028 per share during 2000,
$25.2014 per share during 2001 and $25.00 per share after December 31, 2001 plus
accumulated and unpaid dividends. Each Preferred Share has a liquidation
preference of $25.00 and is convertible at any time into 1.25 common shares of
Chieftain Canada at the option of the holder. Reference is made to Exhibits
4(a), "Form of Certificate of Designation of Preferred Stock of Funding Corp.",
and 4(b), "Form of Subordinated Guarantee Agreement of Chieftain International,
Inc.".

                                    PART IV

ITEM 14. EXHIBITS AND REPORTS ON FORM 8-K

The following is a listing of the financial statements which are included in
this Form 10-K report.

FINANCIAL STATEMENTS

Reference is made to the list of financial statements on page 4 of this report.

EXHIBITS

Reference is made to the Index to Exhibits on page 15 of this report.

REPORTS ON FORM 8-K

The registrant filed no reports on Form 8-K during the fourth quarter of the
year ended December 31, 1999.



                                       7
<PAGE>   10

AUDITORS' REPORT


To the Shareholders of
Chieftain International Funding Corp.

We have audited the balance sheets of Chieftain International Funding Corp. as
at December 31, 1999 and 1998 and the statements of income and retained earnings
and cash flows for each of the years in the three-year period ended December 31,
1999. These financial statements are the responsibility of the Company's
management. Our responsibility is to express an opinion on these financial
statements based on our audits.

We conducted our audits in accordance with Canadian generally accepted auditing
standards. Those standards require that we plan and perform an audit to obtain
reasonable assurance whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements. An audit also includes
assessing the accounting principles used and significant estimates made by
management, as well as evaluating the overall financial statement presentation.

In our opinion, these financial statements present fairly, in all material
respects, the financial position of the Company as at December 31, 1999 and 1998
and the results of its operations and its cash flows for each of the years in
the three-year period ended December 31, 1999 in accordance with Canadian
generally accepted accounting principles.

/s/ PricewaterhouseCoopers LLP
PricewaterhouseCoopers LLP
Chartered Accountants

Edmonton, Alberta
February 3, 2000



                                       8
<PAGE>   11

CHIEFTAIN INTERNATIONAL FUNDING CORP.
(a subsidiary of Chieftain International (U.S.) Inc.)

BALANCE SHEET

<TABLE>
<CAPTION>
December 31,                                                                       1999                 1998
------------                                                                    ----------           ----------
                                                                                            (U.S.$)
<S>                                                                            <C>                  <C>
ASSETS
Current assets:
   Cash                                                                        $   147,982          $   121,495
   Due from affiliated companies                                                 5,392,730            4,572,256
                                                                               -----------          -----------
                                                                                 5,540,712            4,693,751
Investment in preferred shares of Chieftain International (U.S.) Inc.
   at cost (Note 2)                                                             78,500,000           78,500,000
                                                                               -----------          -----------
                                                                               $84,040,712          $83,193,751
                                                                               ===========          ===========

LIABILITIES AND SHAREHOLDERS' EQUITY

Current liabilities:
   Accounts payable and accrued                                                $     5,305          $     6,343

Preferred shares issued (Note 3)                                                63,402,903           63,402,903

Common shareholder's equity:
   Share capital (Note 4)
      Authorized
        10,000,000 common shares, par value $0.01 each
      Issued
        200,000 common shares                                                        2,000                2,000
   Additional paid in capital                                                   14,998,000           14,998,000
   Retained earnings                                                             5,632,504            4,784,505
                                                                               -----------          -----------
                                                                                20,632,504           19,784,505
                                                                               -----------          -----------

                                                                               $84,040,712          $83,193,751
                                                                               ===========          ===========
</TABLE>

APPROVED BY THE BOARD

/s/ S.A. Milner                     Director
--------------------------------------------

/s/ L.G. Munin                      Director
--------------------------------------------



                                       9
<PAGE>   12

CHIEFTAIN INTERNATIONAL FUNDING CORP.

STATEMENT OF INCOME AND RETAINED EARNINGS

<TABLE>
<CAPTION>
Year ended December 31,                                                  1999                   1998                 1997
-----------------------                                               ----------             ----------           -----------
                                                                                               (U.S. $)
<S>                                                                   <C>                   <C>                   <C>
Revenue
   Dividends                                                          $ 5,691,250           $ 5,691,250           $ 5,691,250
   Interest                                                               222,978               205,865               175,599
                                                                      -----------           -----------           -----------

                                                                        5,914,228             5,897,115             5,866,849

General and administrative expenses                                        70,085               176,120                76,553
                                                                      -----------           -----------           -----------

Income before income taxes and dividends on preferred shares            5,844,143             5,720,995             5,790,296

Income taxes (Note 5)                                                      54,000                11,000                34,779
                                                                      -----------           -----------           -----------

Income before dividends on preferred shares                             5,790,143             5,709,995             5,755,517

Dividends on preferred shares                                          (4,942,144)           (4,942,144)           (4,942,144)
                                                                      -----------           -----------           -----------

Net income applicable to common shares                                    847,999               767,851               813,373

Retained earnings, beginning of period                                  4,784,505             4,016,654             3,203,281
                                                                      -----------           -----------           -----------

Retained earnings, end of period                                      $ 5,632,504           $ 4,784,505          $ 4,016,654
                                                                      ===========           ===========           ===========

Net income per common share                                           $      4.24           $      3.84           $      4.07
                                                                      ===========           ===========           ===========
</TABLE>



                                       10
<PAGE>   13


CHIEFTAIN INTERNATIONAL FUNDING CORP.

STATEMENT OF CASH FLOWS

<TABLE>
<CAPTION>
Year ended December 31,                                1999                  1998                  1997
-----------------------                                ----                  ----                  ----
                                                                           (U.S. $)
<S>                                                <C>                   <C>                   <C>
Operating activities:
   Net income applicable to common shares          $   847,999           $   767,851           $   813,373
   Change in non-cash working capital
      Current liabilities                               (1,038)                  567                 1,676
                                                   -----------           -----------           -----------
                                                       846,961               768,418               815,049
Investing activities:
   Advances to affiliated companies                   (820,474)             (692,274)             (850,555)
                                                   -----------           -----------           -----------

Change in cash                                          26,487                76,144              (35,506)

Cash, beginning of year                                121,495                45,351                80,857
                                                   -----------           -----------           -----------

Cash, end of year                                  $   147,982           $   121,495           $    45,351
                                                   ===========           ===========           ===========
</TABLE>



                                       11
<PAGE>   14

CHIEFTAIN INTERNATIONAL FUNDING CORP.

NOTES TO FINANCIAL STATEMENTS

December 31, 1999, 1998 and 1997

Chieftain International Funding Corp. ("Funding Corp."), a special purpose
subsidiary of Chieftain International (U.S.) Inc., was formed in 1992 for the
primary purpose of financing the U.S. business operations of its parent. Funding
Corp.'s income is derived from dividends on preferred shares and interest on
short-term notes, all of which are issued by its parent company, Chieftain
International (U.S.) Inc. The financial statements are expressed in U.S.
currency since the assets and operations of Funding Corp. are denominated in
U.S. dollars.

1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

ACCOUNTING POLICIES

The financial statements of Funding Corp. are prepared in conformity with
Canadian generally accepted accounting principles. The preparation of financial
statements in conformity with generally accepted accounting principles requires
management to make informed judgements and estimates. Actual results may differ
from those estimates. Material differences between Canadian and U.S. accounting
principles which affect Funding Corp. are specifically referred to in these
Notes to Financial Statements.

FINANCIAL ASSETS AND LIABILITIES

Funding Corp.'s financial instruments that are included in the Balance Sheet are
comprised of cash, intercompany receivables, all current liabilities and
preferred shares issued, the fair values of which, other than the preferred
shares issued (see Note 3), approximate their carrying amounts due to their
short-term or demand nature.

INCOME TAXES

Funding Corp. and its parent company file corporate income tax returns on a
consolidated basis. As a result, income taxes payable have been offset by the
parent company's tax losses and are reflected in the amount due from the parent
company.

Effective with the fourth quarter of 1999, Funding Corp. retroactively adopted
the liability method of accounting for income taxes, such method being required
to be adopted no later than 2000 under Canadian generally accepted accounting
principles. Applying this method, deferred income taxes are recognized, using
applicable, enacted income tax rates, for the future income tax consequences
attributable to differences between the financial statement carrying values and
their respective income tax bases. The effect on deferred income tax assets and
liabilities of a change in tax rates is included in income in the period that
includes the enactment date. Deferred income tax assets are evaluated and if
realization is considered "more likely than not", no valuation allowance is
provided.

The retroactive application of this policy had no material effect on Funding
Corp. and therefore no restatement of prior periods has been made.

2. INVESTMENT IN PREFERRED SHARES OF PARENT


On November 6, 1992, Funding Corp. purchased 2,840,000 $1.8125 Redeemable Class
B Preferred Shares at $25.00 per share of Chieftain International (U.S.) Inc.,
its parent company. Subsequent to that date, Funding Corp. purchased an
additional 300,000 of such shares to hold a total of 3,140,000 shares. The
shares pay quarterly dividends at the annual rate of $1.8125 per share. The
shares are redeemable at the option of the parent company at $25.4028 per share
during 2000, $25.2014 per share during 2001 and $25.00 per share after December
31, 2001, plus accumulated and unpaid dividends.



                                       12
<PAGE>   15

3. PREFERRED SHARES

The Articles of Funding Corp. authorize the issue of a maximum of 10,000,000
preferred shares with a par value $1.00 each.

On November 6, 1992, Funding Corp. sold 2,400,000 shares of $1.8125 convertible
redeemable preferred stock at $25.00 per share through an underwritten public
offering in the United States. On December 2, 1992, Funding Corp. sold an
additional 326,700 preferred shares pursuant to an over-allotment option granted
to the underwriters, resulting in a total issuance of 2,726,700 shares. Proceeds
of the issuance of preferred shares, net of offering costs of $4.7 million, were
$63.4 million. The preferred shares are redeemable, at the option of Funding
Corp., at $25.4028 per share during 2000, $25.2014 per share during 2001 and
$25.00 per share after December 31, 2001, plus accumulated and unpaid dividends.
Each preferred share has a liquidation preference of $25.00 and is convertible
at any time at the option of the holder into 1.25 common shares of Chieftain
International, Inc. (the ultimate parent company). Chieftain International, Inc.
has guaranteed dividend, conversion and redemption obligations of Funding Corp.
with respect to the preferred shares.

Canadian generally accepted accounting principles require the disclosure of the
fair value of a financial instrument of this nature and define the fair value as
the amount at which the instrument could be exchanged in a current transaction
between willing parties. The estimated fair value of Funding Corp.'s preferred
shares at December 31, 1999 is $69,530,850 (1998 - $65,781,638), which is the
market value of these preferred shares.

4. SHARE CAPITAL

On August 28, 1992, Funding Corp. issued 100,000 common shares, par value $0.01
each, for net cash proceeds of $1,000 and, on November 5, 1992 issued 100,000
common shares, par value $0.01 each, to its parent for net cash proceeds of
$14,999,000.

5. INCOME TAXES

The actual tax rate differed from the expected tax rate for the following
reason:

<TABLE>
<CAPTION>
Year ended December 31,                                           1999           1998           1997
-----------------------                                           ----           ----           ----
<S>                                                               <C>            <C>            <C>
Expected percentage                                               35.5%          35.5%          35.5%
Deduct the effect of dividends from the parent received by
   the company on a "tax-free" basis                              34.6           35.3           34.9
                                                                  ----           ----           ----
Actual percentage of income tax expense on pre-tax income          0.9%           0.2%           0.6%
                                                                  ====           ====           ====
</TABLE>


6. TRANSACTIONS WITH AFFILIATES

All dividend and interest income of Funding Corp. is received from Chieftain
International (U.S.) Inc. Certain administrative services are provided to
Funding Corp. by Chieftain International, Inc.

7. UNCERTAINTY DUE TO THE YEAR 2000

The Year 2000 Issue arises because many computer systems use two digits rather
than four to identify a year. Date-sensitive systems may recognize the year 2000
as 1900 or some other date, resulting in errors when information using year 2000
dates is processed. In addition, similar problems may arise in some systems
which use certain dates in 1999 to represent something other than a date.
Although the change in date has occurred, it is not possible to conclude that
all aspects of the Year 2000 Issue that may affect Funding Corp., including
those related to customers, suppliers, or other third parties, have been fully
resolved.

                                       13
<PAGE>   16

                                    Exhibits

<TABLE>
<CAPTION>
   Exhibit
    Number         Exhibit
   -------         -------
<S>                <C>
   **  3 (e)       Articles of Incorporation of Funding Corp.
   **  3 (f)       Amended Articles of Incorporation of Funding Corp.
   **  3 (g)       Bylaws of Funding Corp.
   **  4 (a)       Form of Certificate of Designation of Preferred Stock of Funding Corp.
   **  4 (b)       Form of Subordinated Guarantee Agreement of Chieftain International, Inc.
 **** 27           Financial Data Schedule
 **** 99           Form 10-K of Chieftain International, Inc. for the year ended December 31, 1999.

   **              Previously filed as an exhibit to the Registration Statement of the registrant on Form S-1/S-3,
                   File No. 33-51630.
 ****              Filed herewith.
</TABLE>



                                       15
<PAGE>   17

                                   SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange
Act of 1934, the registrant has duly caused this report to be signed on its
behalf by the undersigned, thereunto duly authorized.


CHIEFTAIN INTERNATIONAL FUNDING CORP.


By: /s/ STANLEY A. MILNER
   --------------------------------
   Stanley A. Milner, A.O.E., LL.D.
   President and Chief Executive Officer
   Principal Executive and Financial Officer


Dated: March 15, 2000


Pursuant to the requirements of the Securities Exchange Act of 1934, this report
has been signed below by the following persons on behalf of the registrant and
in the capacities and on the date indicated.


<TABLE>
<CAPTION>
<S>                                <C>                                          <C>
     /s/ D.E. MITCHELL             Director                                     March 15, 2000
-------------------------------
     D.E. Mitchell O.C.

      /s/ S.A. MILNER              President, Chief Executive Officer and       March 15, 2000
-------------------------------    Director; Principal Executive and
  S.A. Milner, A.O.E., LL.D.       Financial Officer

      /s/ S.C. HURLEY              Director                                     March 15, 2000
-------------------------------
        S.C. Hurley

       /s/ H.J. KELLY              Director                                     March 15, 2000
-------------------------------
         H.J. Kelly

       /s/ J.E. MAYBIN             Director                                     March 15, 2000
-------------------------------
         J.E. Maybin

       /s/ L.G. MUNIN              Director                                     March 15, 2000
-------------------------------
         L.G. Munin

       /s/ E.S. ONDRACK            Director                                     March 15, 2000
-------------------------------
         E.S. Ondrack

       /s/ S.T. PEELER             Director                                     March 15, 2000
-------------------------------
         S.T. Peeler

       /s/ R.J. STEFURE            Vice President and Controller                March 15, 2000
-------------------------------    Principal Accounting Officer
          R.J. Stefure
</TABLE>



                                       14
<PAGE>   18

                                Index to Exhibits

<TABLE>
<CAPTION>
   Exhibit
    Number         Exhibit
   -------         -------
<S>                <C>
   **  3 (e)       Articles of Incorporation of Funding Corp.
   **  3 (f)       Amended Articles of Incorporation of Funding Corp.
   **  3 (g)       Bylaws of Funding Corp.
   **  4 (a)       Form of Certificate of Designation of Preferred Stock of Funding Corp.
   **  4 (b)       Form of Subordinated Guarantee Agreement of Chieftain International, Inc.
 **** 27           Financial Data Schedule
 **** 99           Form 10-K of Chieftain International, Inc. for the year ended December 31, 1999.

   **              Previously filed as an exhibit to the Registration Statement of the registrant on Form S-1/S-3,
                   File No. 33-51630.
 ****              Filed herewith.
</TABLE>