Saif Al Gadaffi, heir apparent to Colonel Gadaffi, has said that former intelligence chief Moussa Koussa has “no secrets” to tell over the Pan Am 103 event and says that both the British and the American Governments are already aware of the full circumstances surrounding the destruction of the Boeing airliner over Lockerbie.

Saif Gadaffi, who met with Peter Mandelson to facilitate Abdelbaset Al Megrahi’s repatriation to Libya, has spoken before on the geopolitical aspects of the Megrahi case, denying that Libya had any involvement in the event, but accepted responsibility in order to allow the UN sanctions regime to be lifted.

“The British and the Americans, they know about Lockerbie. They know everything about Lockerbie. There are no secrets anymore,” Gadaffi told the BBC’s John Simpson.

The claim mirrors an earlier revelation made to Dr Jim Swire of UK Families Flight 103.

“One of our number was told by an official on the US Commission of Inquiry, in an aside that: 'Your government and mine know exactly what happened, but they're never going to tell'", Swire says.

Gadaffi added that Koussa is likely to “invent stories” for the British authorities in order to secure his immunity.

“If you press him and say “You have to invent stories in order [for us] to give you immunity, what can he do?. The British Government said he had no immunity unless he cooperated. So of course he will come out with funny stories,” said Gadaffi.

Foreign secretary William Hague would say only that no immunity was being offered to Koussa, and he would be “encouraged” to cooperate with interview requests.

“We will encourage Moussa Koussa to co-operate fully with all requests for interviews with law enforcement and investigation authorities, in relation both to Lockerbie, as well as other issues stemming from Libya's past sponsorship of terrorism, and to seek legal representation where appropriate," Hague said.

Crucially, he added that there was "insufficient evidence to produce further prosecutions, but that may change in future".

Professor Robert Black QC expressed cynicism that Koussa was not being treated as a suspect or witness.

“So there we have it. It is up to Moussa Koussa whether he will speak to Scottish police and prosecutors. But the UK Government will encourage him to do so. Was the Scots' trip to London really worth it?,” he said.

The Crown Office have not yet met with Koussa, and said only that “steps are being taken with a view to arranging a meeting with Mr Musa Kusa at the earliest opportunity in the next few days.”

“As the investigation into the bombing of Pan Am flight 103 remains live, and in order to preserve the integrity of that investigation, it would not be appropriate at this time to offer any further details on the proposed interview or the details of ongoing enquiries."

Veteran Parliamentarian Tam Dalyell has long maintained that 1988 Prime Minister Margaret Thatcher was concealing crucial detail from her public recollections of the Pan Am 103 affair, which she omitted to mention at all in her three volumes of memoirs.

She did however state that the 1986 UK based bombing of Libya destroyed the country’s ability to launch terror attacks against other countries, and that the “much-vaunted Libyan counter attack did not and could not take place..there was a marked decline in Libyan-sponsored terrorism in succeeding years,” she wrote.

An analysis of the discredited Crown case against Abdelbaset Al Megrahi containing further insights from Dalyell and others can be read here.