Phnom Penh  - A French man detained at a Khmer Rouge torture prison said the facility's chief reminded him of his own friends, during his testimony Wednesday as the first witness before Cambodia's UN-backed genocide tribunal.

Francois Bizot, an anthropologist who was imprisoned for three months the ultra-Maoist group's pre-revolutionary prison, expressed sympathy for Kaing Guek Eav, alias Duch, who faces charges of crimes against humanity, torture, premeditated murder and violations of the Geneva Conventions.

"Duch was a man who looked much like many friends of mine, a Marxist who was prepared to surrender his life for the revolution," he said. "I had expected to encounter a monster ... but I realized then things were much more tragic, more frightening."

The Khmer Rouge abducted Bizot in 1971 and detained him at the prison, known as M13, on suspicion of being a CIA spy. Bizot was working as a researcher in Cambodia at the time.

He was interrogated and shackled to iron bars, but was freed after Duch requested his release from his superiors.

Bizot said he spoke regularly with Duch and enjoyed many luxuries not afforded to other prisoners, such as higher quality food and access to bathing facilities. He said he was even thrown a farewell party when he was released.

While Bizot testified that he was not tortured and never witnessed other prisoners being tortured, he added there was evidence of such crimes at the prison.

"Duch, quite unhesitating, (told me) that sometimes he did the hitting, that he would hit the prisoners because they would lie and their testimonies would come up with contradictions. He said that he hated lying, lying was abhorrent to him," he said.

Duch, 66, is the first of five detained Khmer Rouge leaders to go on trial, and while the charges mostly relate to his time as head of the notorious Tuol Sleng prison, this week's hearings have focused on his involvement in acts committed at M13.

The Khmer Rouge ran the prison camp during their insurgency against the US-backed military government from 1971 to 1975.

After overthrowing the government in April 1975, the group sought to transform modern Cambodian culture into an agrarian-socialist utopia and erase history.

Up to 2 million people - a quarter of Cambodia's population at the time - are believed to have died through execution, starvation or overwork during the Khmer Rouge's 1975-1979 reign.

Duch is alleged to have supervised the murders of more than 15,000 people at Tuol Sleng prison, a former high school in Phnom Penh's suburbs.

Bizot has since written a memoir about his time at the prison, called The Gate, and judges asked him whether a sympathetic but unnamed character in the book was in fact Duch.

He replied by saying the character's "dichotomy of good and evil" did not apply to Duch.

"The Gate was written 30 years later through the recollection of my fears and my emotions and sensations back then, which never left me over the past. What I relate concerning Duch and M13 was what I saw with my own sensitivity. It's a literary approach," he said.

Judges asked Duch if he had read the book and he replied that he had not.

The court will continue questioning Bizot when the trial resumes Thursday. (dpa)