Cambodia's United Nations-backed tribunal is hearing charges against a former Khmer Rouge prison chief.  The former Khmer Rouge official has admitted he played a role in the torture and execution of thousands of innocent Cambodians.

The trial of Kaing Guek Eav, better known as "Duch", opened Monday, with charges against him read out in court.

The former chief of Phnom Penh's Tuol Sleng prison is accused of war crimes, crimes against humanity, torture and murder.

This court official says that Duch confirms the use of torture within the prison was systematic and that anyone taken for interrogation would likely be tortured.

At least 12,000 Cambodians were tortured at Tuol Sleng, under Duch's supervision, accused of being traitors to the Khmer Rouge and communism.  Most were later executed.  Some of them were beaten to death with iron bars.

Duch is the only former Khmer Rouge official to admit responsibility for atrocities committed during their brutal 1970s rule and the first to show remorse.

Nic Dunlop is a freelance journalist who discovered Duch in 1999, hiding near the Thai border and using a fake name.  He tells VOA it is difficult to assess whether Duch's regret is genuine.

"He told us, anyway, that he began to feel bad about what was occurring in his prison at that time towards the end," Dunlop said.  "Very much towards the end, like merely a matter of months before the Vietnamese came and liberated Cambodia from the Khmer Rouge. So, it's very difficult to say."

Later this week, Duch is scheduled to make a statement in which his lawyers say he will express some responsibility and shame for what he has done.

The trial, which technically started in February, is expected to last several months.  If he is found guilty, the 66-year-old could face life in prison.

There are four other, more senior, Khmer Rouge leaders in custody who are expected to go on trial later this year.

The tribunal has been plagued by allegations of corruption and political interference to limit the number of former Khmer Rouge leaders brought to justice.

Up to two-million Cambodians died under the Khmer Rouge and its fanatical leader, Pol Pot, who died before he could be brought to trial.