PHNOM PENH - CAMBODIA'S UN-backed war crimes trial on Monday heard its first testimony from one of only a handful of people to have survived the Khmer Rouge regime's notorious main prison.

Van Nath, 63, wept as he gave evidence at the trial of Duch, who is accused of overseeing the torture and extermination of 15,000 people who passed through the hardline communist movement's Tuol Sleng jail.

'The conditions were so inhumane and the food was so little,' said Mr Van Nath, who managed to survive the detention centre only because he was put to work painting pictures that glorified the 1975-1979 regime.

Duch slumped in his chair and looked on while Mr Van Nath recounted his arrival at Tuol Sleng where he was photographed and then shackled with other prisoners.

'There were 20 or 30 of us in each row of shackles. The black clothes we were wearing, we were stripped of those clothes,' Mr Van Nath said.

'We only had three spoons of gruel for each meal. And the spoon was like a coffee spoon, it was not a normal rice spoon. I lost my dignity... Even with animals they would give enough food.' He said that he was arrested and tied up in 1977 by a local official before being taken to the jail, adding: 'I asked him, what did I do wrong. He did not know.'

Earlier in Duch's trial for war crimes and crimes against humanity, the 66-year-old begged forgiveness from the victims after accepting responsibility for his role in governing the jail.

But he has consistently rejected claims by prosecutors that he had a central role in the Khmer Rouge's iron-fisted rule and says he never personally executed anyone.

The court does not have the authority to impose the death penalty, but Duch faces a life sentence for war crimes, crimes against humanity, torture and premeditated murder.

Khmer Rouge leader Pol Pot died in 1998, and many believe the tribunal is the last chance to find justice for victims of the communist regime, which killed up to two million people. -- AFP