Saif Al-Islam Gaddafi, son and one-time heir apparent of toppled Libyan leader Muammar Gaddafi, will be moved to a Tripoli prison within two months and then face trial, the chairman of Libya's National Transitional Council (NTC) said on Sunday.

Three months after his capture in Libya's Sahara desert dressed as a Bedouin tribesman, Saif Al-Islam remains at a secret location in the northwestern town of Zintan, reflecting a wider problem of powerful local militias and a weak central government in the North African country.

In an interview with Reuters, Mustafa Abdul Jalil said authorities were completing the construction of a prison in central Tripoli, begun under the late Muammar Gaddafi, to which Saif Al-Islam would be moved.

"At this moment he is being interrogated and his trial will begin as soon as the prison facility is ready," Abdul Jalil said. "I can't give an exact timeframe in terms of weeks or months for this but it will not be more than two months."

Zintan commanders say they have kept Saif Al-Islam in their remote mountain town, rather than hand him over to the NTC in Tripoli, to spare him the fate of his father.

The older Gaddafi was killed by his captors shortly after being seized in October, his decomposing body put on public display in a Misrata meat locker before given an inglorious secret burial in the Libyan desert.

Saif Al-Islam, a fluent English speaker educated at the London School of Economics, was seen as a the Western-friendly acceptable face of Libya before transforming from liberal reformer to a key figure in his father's fight against rebels seeking his overthrow.

He now faces trial in Tripoli on charges of murder and rape and could face the death penalty if convicted. The International Criminal Court in The Hague has also indicted him for crimes against humanity but Libya says he will be tried in his home country.

"By God's will, Saif al-Islam Gaddafi will receive a fair trial and also all those who are accused in this regard," Abdul Jalil said.   -Reuters