PHNOM PENH - The historic public trial of the man who ran Pol Pot's torture prison is to take a short break, after a dramatic opening three days in which Kaing Guek Eav apologised to his victims and the Cambodian people.

The trial before a United Nations-backed tribunal is taking place before five judges, one of them New Zealand Justice Silvia Cartwright.

Following Tuesday's dramatic apology by Eav, better known by his revolutionary name Duch, yesterday was anti-climatic. The auditorium, packed for two days, was less than half full.

The trial will resume on Monday when the judges will say whether they agree to a defence request to release Duch into a safe house.

Duch's French lawyer, Francois Roux, asked he be moved from the tribunal's specially built jail to a "safe house," as his rights had been violated by his 10-year detention without trial.

Cambodian law prohibits "provisional detention" longer than three years, Roux said.

After his 1999 arrest, Duch spent seven years in a Cambodian military prison, then nearly three years in the tribunal's jail.

Another argument for moving him was that he shared his quarters with four other Khmer Rouge defendants, and he will be implicating some of them during his trial.

Over the coming months witnesses will testify about what went on at Tuol Sleng or S21 torture centre, where an estimated 17,000 people were detained, tortured and executed.

New Zealand Olympic rower Rob Hamill's brother Kerry was tortured at S21 before he was executed, after the yacht he and two others were sailing strayed into Cambodian waters in 1978.

Mr Hamill has been accepted as a civil party, which means his lawyer can ask questions of witness and Duch on his behalf.

Duch on Tuesday admitted the crimes that happened under his watch but qualified that by saying he was only acting under the orders of his superiors.

Mr Hamill told NZPA on Tuesday that it was good Duch had admitted his guilt, but that had to be tempered by the ambition and willingness to do wrong he had shown by his acts.

"Did he ever consider the people he murdered that they, like him, had mothers, fathers, sisters, brothers, or children?"

He wanted to ask Duch what happened to his brother's remains.

The trial is the first of senior leaders in the Khmer Rouge regime under which 1.7 million Cambodians died to be heard before the UN-backed dual international Cambodian Court.

Duch faces charges including crimes against humanity, breaches of the Geneva Convention and violations of the Cambodian penal code including premeditated murder.

Maggie Tait travelled to Cambodia with the assistance of the Asia New Zealand Foundation.