BP’s troubles in the US intensified when the company shut 12 Alaskan oil wells on Tuesday after whistleblowers said some 50 had been leaking.

Robert Malone, president of BP America, said it would close the wells after workers at its Prudhoe Bay oil field told the Financial Times about the leaks. Mr Malone said the wells would be shut “even though we have no reason to believe... the continued operation of these wells poses a risk to workers or the environment’’.