Foreign Secretary William Hague has told the US there was “no evidence” to support claims the release of the Lockerbie bomber was linked to BP oil deals.
Mr Hague wrote to Secretary of State Hillary Clinton amid renewed questions in Washington over the Scottish Executive's decision to return Abdelbaset Ali Mohmed Al Megrahi to Libya last year.
A group of Democrat senators is demanding an inquiry into claims the oil giant lobbied for the release to smooth a deal and an influential senate committee is also to examine the case.
The fresh attention on BP — already battling the political fallout of the Gulf of Mexico spill — threatens to overshadow David Cameron's first visit to Washington as Prime Minister tomorrow.
Mr Hague has promised to “engage constructively” with his counterpart, but reiterated that the British Government considered the release “a mistake”.
Megrahi, the only man convicted of involvement in the bombing of Pan Am flight 103, which killed 270 people in 1988, was freed on compassionate grounds after being diagnosed with terminal cancer.