US President Barack Obama and UK?prime minister David Cameron were expected to discuss London-based BP Plc and the Gulf of Mexico oil spill last night as stormy weather raised fears that clean-up operations could be disrupted.

The oil spill, the worst in US history, is overshadowing the first meeting between Obama and Cameron since the prime minister took office last month, which will take place on the sidelines of the G8/G20 summit in Canada.

The energy giant's share price is trading at 14-year lows after falling sharply again on Friday, when Cameron offered his strongest comments yet on the issue.

"It is ... in all our long-term interests that there is some clarity, some finality, to all of this, so that we don't at the same time see the destruction of a company that is important for all our interests," Cameron told Canadian broadcaster CBC.

"This is a vital company for all of our interests ... BP itself wants to cap the well and clean up the spill and compensate those who have had damages," Cameron said.

Obama has been highly critical of BP while his own poll ratings have fallen, in part because of perceptions that his handling of the crisis has been too slow.

British business and shareholder groups have meanwhile clamoured for Cameron to defend the company. But Cameron insisted he believed the matter called for gentle persuasion. "This isn't an issue between Britain and America. This is about BP doing what it should, but also being treated in a way that enables it to go forward," he told reporters.

Far from the high-level talks, those involved in the clean-up and containment efforts were anxious about the formation of the first tropical storm of the 2010 Atlantic hurricane season in the western Caribbean, a development that could disrupt such operations for weeks.

Tropical storm Alex was located 400km east-southeast of Chetumal, Mexico, and moving west-northwest at 13 kph. Its path would take it towards Belize and over the Yucatan Peninsula during the weekend and then into the Gulf of Mexico, where workers are battling to contain the spill, though it was too early to tell if it would affect such operations.