Jack Straw and a former MI6 official who helped BP to win valuable oil contracts in Libya have been summoned to appear before a US Senate committee investigating the company's role in the release of the Lockerbie bomber.
Mark Allen, who became a special adviser to BP after leaving the intelligence services, will be asked about a series of communications he had with Mr Straw, the former Labour Justice Secretary, over a prisoner transfer agreement between Britain and Libya.
Mr Straw has been asked to appear at the hearing in Washington on July 29.
Mr Allen, who also had private meetings with Colonel Gadaffi, both for BP and earlier for MI6, will appear before the Senate's foreign relations committee next week. It is understood that Tony Hayward, the chief executive of BP, has also been asked to appear.
If BP refuses the request, it is likely to provoke more American anger towards the company.
Senators announced earlier this month that they would hold a hearing to analyse BP's potential role in the release of Abdelbaset al-Megrahi.
The oil company has admitted lobbying the British Government to introduce a prisoner transfer agreement with Libya.
However, the final decision to free al-Megrahi in August last year was taken by Scottish ministers on the basis that he had only three months left to live.
He is still alive and the Scottish Executive is now under pressure to release confidential medical reports setting out the prognosis.