Prime Minister David Cameron refused to criticize the United States, however, saying he sympathized with its “frustration” in dealing with its worst environmental disaster in memory. But the chancellor of the Exchequer, George Osborne, signaled careful support for BP, saying that he had spoken to its chief executive, Tony Hayward, and that it was important to remember “the economic value BP brings to people in Britain and America.”

BP is the third largest oil company in the world, after ExxonMobil and Royal Dutch Shell, with 80,000 employees worldwide as of last December, sales of $239 billion in 2009 and a market value  even after the recent losses  of more than $100 billion. At a time when Britain is desperate to reduce its deficit, BP is a huge contributor to British tax revenue, paying nearly $1.4 billion in taxes on its profits last year.

Its reputation for reliability and its generous dividends have long made it a favorite of British pension funds. The company’s dividend payments accounted for about 13 percent of the dividends handed out by British companies last year, according to FairPensions, a London-based charity.

Some Britons are irked at President Obama’s seeming determination to refer to the company as “British Petroleum”  even though it jettisoned that name in favor of initials years ago. In any case, they point out, it is truly a multinational company, traded on both the New York and London stock exchanges, with British and American nationals on its board of directors.

BP also has extensive holdings in the United States. It merged with Amoco, the former Standard Oil of Indiana, in 1998, and about 40 percent of its shares are held by American investors. It owns a refinery in Texas City, Tex., that is one of the world’s largest, and a 50 percent interest in the Trans Alaska Pipeline, in addition to a huge gasoline marketing operation.