The outgoing chief executive of BP has refused US officials' requests to appear at a hearing next month over the release of the Libyan man convicted of bombing Pan Am Flight 103 over Lockerbie.
Tony Hayward told Senator Robert Menendez, a Democrat, in a letter that he is focusing on ensuring a smooth transition of leadership at the company and will be unable to testify.
The Senate Foreign Relations Committee is looking into whether the British-based oil company had sought Abdelbaset Al Megrahi's release to help get a 900 million dollar (£583 million) exploration agreement with Libya off the ground.