Washington, D.C. 20549

                                    Form 6-K

                            Report of Foreign Issuer

                      Pursuant to Rule 13a-16 or 15d-16 of
                       the Securities Exchange Act of 1934

                       for the period ended 29 June 2004

                                    BP p.l.c.
                 (Translation of registrant's name into English)

                    (Address of principal executive offices)

     Indicate  by check mark  whether the  registrant  files or will file annual
     reports under cover Form 20-F or Form 40-F.

              Form 20-F        |X|          Form 40-F
                         ---------------               ----------------

     Indicate by check mark whether the registrant by furnishing the information
     contained in this Form is also thereby  furnishing  the  information to the
     Commission  pursuant to Rule 12g3-2(b) under the Securities Exchange Act of

                    Yes                            No        |X|
                         ---------------               ----------------

June 29, 2004


BP's 2003 Form 20-F, filed with the US Securities and Exchange Commission (SEC)
in Washington, D.C. late yesterday, shows total proved reserves reported under
SEC requirements are 23 million barrels more than those presented in its 2003
Annual Report and Accounts to Shareholders issued in March.

BP's 2003 Form 20-F - which reconciles its financial accounts, published under
UK Generally Accepted Accounting Practice (GAAP), with US Generally Accepted
Accounting Principles - reports proved reserves of 18.361 billion barrels of oil
equivalent, compared with 18.338 billion barrels in its 2003 Annual Report and

BP said that it considers the 23 million barrel difference, which represents
some 0.1 per cent of its total proved reserve base, including equity accounted
entities, to be immaterial.

As a UK-registered company reporting under UK GAAP, BP determines its proved
reserves under the UK Statement of Recommended Practice, Accounting for Oil and
Gas Exploration, Development, Production and Decommissioning Activities (SORP).
In estimating reserves, it uses long-term planning prices to determine the
commercial viability of upstream resources. For 2003 these prices were $16 a
barrel for oil and $2.70 per thousand cubic feet for natural gas.

In contrast, SEC guidelines require the use of year-end market prices which, as
of December 31, 2003, were $30.10 a barrel for Brent crude and $5.76 per
thousand cubic feet for Henry Hub gas.

Using year-end prices and assuming they apply to the end-of-field life has the
effect of increasing the volumes of oil and gas likely to be recovered
economically from reservoirs, thus adding to proved reserves. On the other hand,
using year-end prices has the effect of decreasing reserves in the case of
production-sharing agreements (PSAs) where a higher oil price results in lower
volume entitlement.

BP said that use of year-end pricing and some changes in the way it applies SEC
interpretations of SEC regulations relating to field fuel gas and the use of
technology in determining reserves, while giving rise to larger variations on a
regional basis in its proved reserves, accounted for the upward difference of
only 23 million barrels on an aggregate basis between its 20-F and UK SORP

The company believes that its long-term planning price assumptions provide the
most appropriate basis for estimating oil and gas reserves and will continue to
use this basis for its UK reporting.

The company said it had received comments from the SEC on its 20-F Filing for
2002 and that the SEC review process was still ongoing.

A table setting out BP's 2003 Form 20-F estimated reserves on a regional basis,
with comparable estimates under UK SORP, are included with this release as Notes
to Editors. Copies of the BP 2003 Form 20-F and the BP 2003 Annual Report and
Accounts (ARA) are available at and

Notes to editors:

- The figures below are total proved reserves for crude oil plus
natural gas, for subsidiaries plus equity-accounted entities, in millions of
barrels of oil equivalent (mmboe):

        BP proved         Proved reserves     Difference/     Difference as
        reserves in 2003  reported in 2003     mmboe          % of total
        ARA/mmboe         Form 20-F/mmboe                     proved reserves

UK               1,496      1,647                151             0.8%
Rest of Europe     564        625                 61             0.3%
USA              5,624      5,956                332             1.8%
Rest of Americas 4,330      4,225               (105)           (0.6%)
Asia Pacific     1,049      1,063                 14             0.1%
Africa           1,635      1,310               (325)           (1.8%)
Russia           1,794      1,805                 11             0.1%
Other            1,846      1,730               (116)           (0.6%)
Total           18,338     18,361                 23             0.1%

- ENDS -


Pursuant to the requirements 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.

                                         BP p.l.c.

Dated: 29 June 2004                               /s/ D. J. PEARL
                                                  D. J. PEARL
                                                  Deputy Company Secretary