Duch - whose real name is Kaing Guek Eav - politely answered questions about the organisation of Tuol Sleng prison but strongly denied he created the list of orders that remains on display at the site, now a genocide museum.

"The discipline of security, which has 10 rules...was fabricated by the Vietnamese when they came in (and toppled the Khmer Rouge in 1979)," Duch told the court.

Duch, 66, said he first saw the list of orders last year, when investigators brought him to the prison in the Cambodian capital Phnom Penh to re-enact his crimes.

A large board displaying the list on how to behave during interrogations, which includes an order that prisoners cannot cry when flogged or subjected to electric shocks, is still posted in the main courtyard at Tuol Sleng.

The list also tells prisoners to sit still and wait for orders, answer questions immediately without waiting for time to reflect, and warns them of further lashes or electric shocks if they fail to comply.

Duch is charged with crimes against humanity, war crimes, torture and premeditated murder over the extermination of around 15,000 people between 1975 and 1979 at Tuol Sleng and the nearby "Killing Fields".

He apologised last month when his trial started, accepting blame for overseeing the horrors of the prison.

However he has denied prosecutors' claims that he played a central role in the Khmer Rouge's iron-fisted rule, and maintains he never personally executed anyone.

He faces life in jail but the court does not have the power to impose the death penalty. Four other senior leaders from the regime are scheduled to be tried within the next year.

Many believe the UN-sponsored tribunal is the last chance to find justice for victims of the regime, which killed up to two million people through starvation, overwork, torture and execution.

The Khmer Rouge were ousted by Hanoi-backed forces in 1979, who discovered Tuol Sleng and established the facility as a museum to display the regime's crimes.

Agence France Presse - April 29, 2009