BP says Tony Hayward will step down as chief executive officer from October 1, to be succeeded by American Robert Dudley.

In a statement accompanying its earnings update today, BP says the decision was made by "mutual agreement."

BP also reports it has taken a pretax charge of $32.2 ($NZ43.91) billion for the Gulf of Mexico spill, and plans to sell assets for up to $30 billion over the next 18 months.

The company says Dudley will be based in London when he takes up his appointment and will hand over his present duties in the United States to Lamar McKay - the chairman and president of BP America.

Hayward will remain on the board until November 30 and BP plans to nominate him as a non-executive director of its Russian joint venture TNK-BP.

Meanwhile, Greenpeace activists have been shutting down BP service stations across London this morning (this evening NZT) in protest at the company's handling of the Gulf of Mexico oil spill.

The organisation's UK website says it aims "to close dozens down this morning".

Greenpeace chose today for the protest because the announcement about Hayward stepping down was expected.

Greenpeace is updating how many stations have been shut down on its website. The latest figure is 46.

But a BP spokesman told British media the activists had only managed to close down around a dozen service stations, adding that they would be reopened as soon as it was safe to do so.

He told the Independent the stunt was "an irresponsible and childish act which is interfering with safety systems".

- NZ Herald staff