A prominent political prisoner in Libya is facing a possible death sentence for slandering leader Muammar Gaddafi, US-based Human Rights Watch says.
Fathi al-Jahmi was first detained in October 2002
Fathi al-Jahmi, 64, has been held by state security for more than two years after a series of outspoken comments about Col Gaddafi and the regime.
Human Rights Watch (HRW) called for his immediate release.
Libya's relationship with the US has improved dramatically since it renounced its WMD ambitions in 2003.
"The Libyan government is taking great pains to introduce a democratic face to the world," HRW's Middle East director, Sarah Leah Whitson, said.
"But it appears willing to execute people for criticising its leader or talking with a foreign official, which shows how far it has to go."
Mr Jahmi was first arrested in October 2002 after he criticised the government and Col Gaddafi, and called for free elections, a free press and the release of political prisoners, HRW said.
He was sentenced to five years in prison, but was released in March 2004 after a US senator appealed on his behalf in a meeting with Col Gaddafi.
However, he was re-arrested in the same month after giving a television interview in which he repeated his calls for Libya's democratisation.
According to the Libyan government, Mr Jahmi's trial began in late 2005, but the authorities have not made the charges known, HRW reported.
Mr Jahmi told HRW officials who visited him in detention in May 2005 that he had been accused of trying to overthrow the government, insulting Col Gaddafi and contacting foreign authorities, after he talked to a US diplomat.
All those charges carry the death penalty, HRW said.
The New York-based group said Libya's internal security agency head, Tommy Khaled, told them Mr Jahmi was being held in a special detention centre for his own safety because he is "mentally deranged".
"Libya has renounced terrorism and weapons of mass destruction in its efforts to rejoin the international community," Ms Whitson said.
"Now it should take another step and let peaceful critics speak their minds".
Although relations between Tripoli and Washington have warmed in recent years, Libya still remains on the US list of states that sponsor terrorism.