Secret talks between Tony Blair and Colonel Muammar Gaddafi have led to hopes that the Lockerbie bomber will soon be returning to his Libyan homeland, according to the Libyan leader's son.

On a visit to France, Saif al Islam Gadaffi said the talks, in the closing weeks of the British leader's premiership, were also linked to an improvement in relations between Europe and Tripoli that yesterday saw the first news of an arms deal since an embargo was lifted three years ago.

Mr Blair failed to inform the Scottish Executive about his memorandum of understanding with the Tripoli government on transfer of prisoners, provoking strong criticism from First Minister Alex Salmond when he found out.

Abdel Basset Ali Mohmed al Megrahi is the former Libyan government agent whose release the Tripoli government has made clear is now its top priority. He was found guilty in 2001 of the murder of 270 people in the 1988 bombing of airline passengers flying from London to New York, including 20 killed by debris in and around Lockerbie. He is held in Greenock prison.

In an interview for the French newspaper Le Monde, Saif al Islam Gadaffi made the link between Mr Blair's visit and the return of al Megrahi. He went on to indicate there is a further link with the release of five Bulgarian nurses and a Palestinian doctor convicted in Libya of infecting Libyan children with HIV and sentenced to death, but freed last month.

The 35-year-old Gadaffi, visiting Nice, added that Libyan officials were in London to discuss the agreement with Britain about a month ago.

However, a spokesman for the Foreign Office in London said: "Any decision on Mr Megrahi would be a matter for the Scottish courts and the Scottish authorities.

"There is no deal being done".

An executive spokesman said: "Prisoner transfer is a matter for Scottish ministers to decide. Ministers' absolute priority is ensuring that the independent legal process that is underway takes its proper course."

The Megrahi case is to go before Scotland's Court of Appeal which will decide whether to accept a recommendation from the Scottish Criminal Cases Review Commission that the evidence in the Lockerbie trial should be re-examined.

While the diplomatic pressure is stepped up, Scottish judges are not expected to rush their decision. With the need for both sides to prepare their cases, it is expected to be next year before any appeal hearing could begin.

A source close to Mr Salmond said the picture emerging from Libya shows the confusion and misunderstanding that came from Mr Blair's style of informal government. But since Mr Salmond met Justice Secretary Jack Straw last month, "there is now an understanding of each other, clarity and sharing of information".

However, it is not clear if the executive has begun to play a role in the discussion of the prisoner transfer agreement, due to be completed next May.