The joint BP-US government response team said there were doubts that the oil had drifted all the way from the spill.

BBC: Gulf oil spill reaches Texas as tar balls wash ashore

Facing challenges in other parts of the world, and having sold its Russian joint venture TNK-BP, it sees the US as central to its plans for future growth.

CNN: BP claims it now leads the way on safety

We then worked -- a group of us worked with a group from BP, including the chairman, Mr. Hayward and others to make that happen.

WHITEHOUSE: Press Briefing on BP Oil Spill

In a 30-minute phone call, the US president said he recognised BP was a multinational company and he had no interest in undermining its value.

BBC: BP criticism not about nationality, says Obama

There is also a chance that BP will end up not paying dividends this year and it is almost certain that the amount BP is having to pay out for the clean-up in the US will eventually affect the dividend.

BBC: Why is BP important to the UK economy?

For the US government it's all the resources they're spending on the trial - particularly if BP is not found grossly negligent.

BBC: BP oil spill trial told it 'put profits over safety'

Four US senators are calling for an investigation into allegations that oil firm BP lobbied for the early freeing of Abdelbaset al-Megrahi, who was convicted of the 1988 bombing of Pan Am Flight 103 which killed 270 people.

BBC: Barack Obama: UK relationship is 'truly special'

In its settlement last year with the US Department of Justice of the criminal charges against it, BP admitted that negligence on the part of its employees -- along with other companies -- was a "proximate cause" of the accident.

CNN: BP claims it now leads the way on safety