Saif al-Islam, Colonel Gaddafi?s son, has had the ends of his right-hand forefinger and thumb amputated before facing two trials on corruption and war crimes charges, the first of which could begin as early as next month, The Times has learnt.

Human rights groups have expressed mounting concern for the legal rights of Mr Gaddafi, who was captured on November 19 and has been held in solitary confinement without access to lawyers.

Researchers from Human Rights Watch (HRW), who met him for 30 minutes last week, said that he had the top knuckle of his thumb and forefinger removed by doctors in his prison cell. He has a further injury to the adjacent middle finger.

Mr Gaddafi told them that the digits were removed because injuries sustained in a Nato airstrike before his capture had become gangrenous. He is still being held by the local militia in Zintan in the Nafusa Mountains in western Libya. The group has proved unwilling to hand him over to the central government.

The head of the rebel government council in Zintan, which has a population of 30,000, told The Times yesterday that they were still interrogating Mr Gaddafi and that he would not be allowed access to a defence lawyer until their questioning was complete.

?He is not allowed to make any requests [for a lawyer] before the investigation is finished,? said Othman Turkhi. ?During this period he is not allowed to talk to anybody. It is not my decision, it is the Libyan regulations.?

HRW said that international standards required that a prisoner should have access to a lawyer within 48 hours of capture. Mr Gaddafi?s main complaint was that he was being held in total isolation, it said.

HRW representatives said Libyan authorities claim to have ?very strong? evidence against him, which is thought to include recordings of phone calls.

?Various officials told us they had very strong evidence against Saif for wartime abuses,? said Fred Abrahams, who met him in Zintan. ?They . . . talked about recordings. They also said they had strong evidence for prewar corruption.?

Abdul Rachman Busin, a spokesman for the National Transition Council central government in Tripoli, said: ?If he has not had access to a lawyer yet it will be done in the next few days. I was informed of this a couple of days back because his trial is due to be starting soon, possibly within a month, possibly within January.?

Mr Abrahams said that such a timeframe would be ?shockingly fast?.

Nick Kaufman, an Israeli lawyer, has been hired by the Gaddafi family in exile and is expected to represent Mr Gaddafi, though without meeting the prisoner he cannot be appointed formally.

Western diplomatic sources said that the corruption charges could be heard before those for crimes against humanity, for which there are already outstanding warrants from the International Criminal Court(ICC).

Libya?s rebel government supported United Nations Resolution 1970 which accepted the jurisdiction of the ICC in relation to alleged crimes against humanity committed by Muammar Gaddafi, who died in October, Saif al-Islam, and Abdullah al-Senussi, the former chief of intelligence.

Mustafa Abdul Jalil, the new Libyan head of state, told HRW that his Government had retained the services of a British law firm to argue before the ICC that the most serious charges against Gaddafi family members should be heard before a Libyan court.

Officials in Zintan told The Times that Mr Gaddafi would be handed to the central government if a request was made. However, federal officials said privately that the Zintan militia remained the most powerful political force in the capital. The day after Zintan fighters captured Mr Gaddafi in the south of the country, its commander, Osama al-Juwali, was made defence minister of the new government.

The British Foreign Office said: ?We welcome the fact that the Libyan government is liaising closely with the ICC and we await details of where and when Saif will face trial. It is important that any trial is in line with international standards.?