London: The London-educated Saif Al Islam Gaddafi, 39, always denied that he played an active role in politics, but he holds the key to the secrets of his father's despotic regime.

His trial could prove deeply embarrassing if he chooses to reveal details of his once-cosy relations with British politicians, including Tony Blair and Peter Mandelson, the former business secretary.

Mohammad Al Alagi, Libya's interim justice minister, said last week that Saif will be placed on trial in Libya and faces the death penalty. With little to lose, Saif may decide from his desert prison in Zintan to spill the beans on business deals and political promises made to the regime over the past decade.

Blair, who was described by Gaddafi Jr as a close personal friend of the family, may face searching questions if Saif goes ahead and reveals the secrets of their deals, including oil contracts and the release of Abdul Basit Al Megrahi, the Lockerbie bomber.

Saif was his father's point man on the settlement of the bombing of Pan Am flight 103 in 1988 which killed 270 people. His detailed knowledge of the negotiations that involved British diplomats and Mousa Kousa, his father's chief of intelligence, could prove explosive. The questions of who knew what, and who did what, have never been answered.

Abdul Raheem Al Keeb, Libya's new prime minister, decided to try Saif in Libya rather than at the International Criminal Court in the Hague where he is wanted for crimes against humanity.

The International Criminal Court chief prosecutor, who visited Libya last week, said Libya can try Saif but the Hague court judges will be involved in it. Saif denied earlier reports that he had offered to give himself up to the Hague court. "It's all lies. I have never been in touch with them," he said.

Among the secrets he could unlock are the machinations that may have gone on under the former Labour government ahead of the release of Al Megrahi.

The release happened after Blair's notorious "deal in the desert" with Muammar Gaddafi paving the way for multi-million-pound oil contracts with Shell and BP.

— The Times Newspapers Limited, London 2011