The former head of the Khmer Rouge's most notorious torture centre sat behind protective glass Wednesday as judges held a closed-door meeting on when to start testimony at Cambodia's long-delayed genocide tribunal in Phnom Penh.

Kaing Guek Eav, known as Duch, is charged with crimes against humanity and has admitted guilt.

He is the first of five defendants who belonged to a close-knit, ultra-communist regime that ruled Cambodia in the 1970s and turned it into a vast slave labour camp in which 1.7 million or more people perished.

Duch oversaw the S-21 prison in the capital Phnom Penh — previously a school, now the Tuol Sleng genocide museum — where 16,000 men, women and children were tortured and killed. Only a handful survived.

Duch's case before the United Nations-assisted tribunal opened Tuesday, but the hearing so far has been procedural, and he did not speak to the panel.

Full trial to start in March

The pretrial proceedings will lay the groundwork for the full trial expected to begin in March.

Wednesday's proceedings started in private, with judges holding a closed-door session to discuss the witness list, Mao Vuth, a tribunal co-ordinator said.

"I think we've started on a firm and solid foundation," said Helen Jarvis, public affairs chief for Extraordinary Chambers in the Courts of Cambodia.

"I think we've shown technically that the court and the staff are equipped and ready to go. And I think judicially too, the judges have shown that they are certainly on top of the case, as it were."

The prosecution said it will present 33 witnesses over 40 days, while the defence wants to have 13 witnesses testify over 4½ days. Once the number of witnesses is settled, judges can set specific trial dates and put Duch on the stand.

Duch, his lawyers and the judges' bench were protected from the public gallery by a thick Plexiglas-type barrier.

Duch only defendant to express remorse

The 66-year-old Duch is the only defendant to have expressed remorse for his actions.

He is accused of committing or abetting a range of crimes, including murder, torture and rape. He did not address the court Tuesday but he again voiced regret through his lawyer.

"Duch acknowledges the facts he's being charged with," his French lawyer Francois Roux said at a press briefing after Tuesday's court session.

"Duch wishes to ask forgiveness from the victims but also from the Cambodian people. He will do so publicly. This is the very least he owes the victims."

The tribunal said in an indictment in March that "Duch necessarily decided how long a prisoner would live, since he ordered their execution based on a personal determination of whether a prisoner had fully confessed" to being an enemy of the regime.

In one mass execution, he gave his men a "kill them all" order, the indictment said. In another incident involving 29 prisoners, he told his henchmen to "interrogate four persons, kill the rest," it said.

After the fall of the Khmer Rouge, Duch disappeared for two decades, living under two other names and converting to Christianity before he was located in northwestern Cambodia by a British journalist in 1999.

Long wait for justice

Kan Hann, 55, who lives in the same district of Kampong Thom province in central Cambodia where Duch grew up, said he came to the trial because his brother and sister died of starvation and overwork under the Khmer Rouge.

"My dream has come true now as I have been waiting for the trial for 30 years," he said.

Duch's trial began 13 years after the tribunal was first proposed and nearly three years after the court was inaugurated.

"This is a very significant day for Cambodia and the world," co-prosecutor Robert Petit told reporters. "Today's proceedings bode well for the commitment of all parties to seek justice for the Khmer Rouge."

Slow pace of tribunal criticized

The tribunal, which incorporates mixed teams of foreign and Cambodian judges, prosecutors and defenders, has drawn sharp criticism.

Its snail's-pace proceedings have been plagued by political interference from the Cambodian government, as well as allegations of bias and corruption.

The Cambodian side in the tribunal recently turned down recommendations from the international co-prosecutor to try other Khmer Rouge leaders, as many as six according to some reports.

"The tribunal cannot bring justice to the millions of the Khmer Rouge's victims if it tries only a handful of the most notorious individuals, while scores of former Khmer Rouge officials and commanders remain free," New York-based Human Rights Watch said Monday.

Others facing trial are Khieu Samphan, the group's former head of state; Ieng Sary, its foreign minister; his wife, Ieng Thirith, who was minister for social affairs; and Nuon Chea, the government's chief ideologue.

All four have denied committing crimes.