Scotland's First Minister Alex Salmond has denied newspaper reports that the release of Lockerbie bomber Abdelbaset Ali al-Megrahi had any links to UK trade talks with Libya.
It is being reported that British Justice Secretary Jack Straw decided two years ago that Megrahi should not be exempt from a prisoner transfer agreement with Libya.
He cited national interest in a series of letters to Scotland's Justice Secretary who released Megrahi on compassionate grounds.
Mr Straw has described as 'simply untrue' accusations from the Liberal Democrats that the letters indicate he wanted to safeguard Britain's commercial interests.
A report in the Sunday Times says a stalled oil deal was ratified by the Libyans six weeks after the British government dropped its bid to exclude Megrahi from the prisoner transfer agreement.
In one of the letters, Mr Straw wrote: ‘I had previously accepted the importance of the Megrahi issue to Scotland and said I would try to get an exclusion for him on the face of the agreement.
‘I have not been able to secure an explicit exclusion.
‘The wider negotiations are reaching a critical stage and, in view of the overwhelming interests of the United Kingdom, I have agreed that in this instance the (prisoner transfer agreement) should be in the standard form and not mention any individual.’
Last week Megrahi, who has terminal prostate cancer, was allowed to leave Greenock prison to go home to Libya.
The man who was convicted of murdering 270 people in the December 1988 bombing of Pan Am 103, returned to a hero's welcome.
The bomber was released on compassionate grounds and not as part of the prisoner transfer agreement.
But the disclosure of Mr Straw's letters by the Sunday Times is likely to raise questions about the government's position on Megrahi's return to Libya earlier this month.
He had served just eight years of a minimum 27 year sentence.
The scenes provoked international condemnation.
