BP and British officials have been accused of "stonewalling" attempts by the US Senate to investigate the release of the Lockerbie bomber. American politicians wanted to question their counterparts in the British Government as well as senior figures at the oil giant over allegations that BP lobbied for the early release of Abdelbaset al-Megrahi to smooth an oil deal with Libya. Senator Robert Menendez has postponed a hearing on the issue because key witnesses refused to appear. The Senate committee had called two Scottish officials, former British Justice Secretary Jack Straw and two BP executives - including departing chief executive Tony Hayward - but all had declined to testify. Mr Menendez said: "It is utterly disappointing and I think pretty outrageous that none of these key witnesses will cooperate with our request to answer questions before the Senate Foreign Relations Committee. They have stonewalled," BP Plc's newly named chief executive on Tuesday called the Gulf oil spill a "wake-up call" for the entire industry. Bob Dudley, who will replace gaffe-prone Tony Hayward as CEO on October 1, said safety would be among his highest priorities as he tries to refurbish the oil company's battered reputation.