Libya is confident it will be exonerated of any role in the Lockerbie bombing and has made the release of its jailed agent Abdelbaset Ali Mohmed al Megrahi its top priority, one of the country's leading officials said yesterday.

Saif al-Islam, the most influential son of Libyan leader Muammar Gaddafi, said Megrahi's return was more important than reclaiming the £1.35bn Libya agreed to pay in compensation for the terrorist atrocity.

However, it was unclear last night whether al-Islam, one of the key players behind normalising Libya's relationship with the West, was referring to the alleged negotiations on prisoner transfer between Britain and Libya before Tony Blair's exit as Prime Minister.

In an interview conducted with Reuters news agency during a visit to France, al-Islam said: "The top of our priority is the return of al Megrahi and not the return of the money because I think he is more important than the money."

Al-Islam, 35, who runs a charitable foundation involved in Libya's long efforts to end its international isolation, added: "We are confident one day it will be proved to the world that we had nothing to do with Lockerbie."

Libya's return from international diplomatic exile received a boost earlier this month with the release of five Bulgarian nurses and a Palestinian doctor sentenced to death in 1998 after being found guilty of deliberately infecting 400 children with HIV.

Their release, after more than eight years in jail, was said to be part of a deal brokered by Mr Blair which included the transfer to a Libyan prison of Megrahi, who is serving his 27-year sentence in Greenock Prison after being convicted of the 1988 atrocity in which 270 people were killed. He has since had his case referred to the Court of Appeal.

Professor Robert Black, an expert who has followed the Lockerbie case, said he did not know whether al-Islam had been involved in the prisoner transfer negotiations, but said that no deal would progress without the explicit backing of the Scottish Executive.

He said: "The whole point of the controversy is that the ultimate decision is for the Scottish Executive, not the Foreign Office or Prime Minister. Any assurances Tony Blair may have given are not worth much without Alex Salmond's approval."

Tam Dalyell, former MP and father of the House of Commons, said he agreed Megrahi would eventually be released but that this would be a result of his judicial appeal. "What is essential is that there is an international element in the appeal," he said.

"I saw Mr Megrahi yet again on June 6 and he emphasised to me that of course he wanted to return to his five children and wife but he wanted to go back an innocent man."

Al-Islam also said that some issues still block full normalisation with America despite the release of the six foreign medics. Asked to name some of the issues, he said "La Belle" - a reference to a Berlin club frequented by members of the US military where three people were killed and 200 wounded in a 1986 bombing Washington blamed on Libya.