Scotland's First Minister Alex Salmond has written to US senators who are calling for an inquiry into the release of the Lockerbie bomber.
Abdelbaset Ali al-Megrahi, the man convicted over the 1988 atrocity in which 270 people died, was released by the Scottish government in August 2009.
Mr Salmond said the Scottish government made the decision on "compassionate grounds" as Megrahi is terminally ill.
He said there were no representations from oil giant BP on the matter.
Libyan Megrahi is the only man to have been convicted of the bombing of Pan Am flight 103 on 21 December 1988.
He was released from a Scottish prison having been given three months to live due to prostate cancer but is still alive almost a year later.
Some US senators suspect that BP lobbied for Megrahi's release to aid its chances of getting oil deals with Libya.
UK Prime Minister David Cameron, on a visit to the US, said the decision to free Megrahi on compassionate grounds was "completely wrong".
However, he said he had seen no evidence the Scottish government had been "swayed" by lobbying from BP.
Scotland's first minister has now written to John Kerry, chairman of the US Senate Committee on Foreign Relations.
Mr Salmond said the decision to release Megrahi was made with "integrity" and following a "clear legal process".
He wrote: "I can say unequivocally that the Scottish government has never, at any point, received any representations from BP in relation to al-Megrahi."
Mr Salmond has previously criticised former UK prime minister Tony Blair for negotiating a prisoner transfer agreement (PTA) with Libya in 2007.
The agreement, which was not invoked for Megrahi's release, gave rise to suspicions of "deals in the desert", Mr Salmond said.
In the letter to the US senators, Mr Salmond repeated his opposition to the prisoner transfer agreement.
He said: "As was highlighted last year, the Scottish government rejected the application for transfer of al-Megrahi under the PTA specifically on the basis that the US government and families of victims in the United States had been led to believe that such a prisoner transfer would not be possible for anyone convicted of the Lockerbie atrocity.
"If your committee is concerned about BP's role or the PTA then it is BP and the previous UK administration that should be the focus of your inquiries."
Mr Salmond added: "There is nothing the Scottish government can add to this since we have had no contact with BP at any point in the process of considering al-Megrahi's position."