A leading Khmer Rouge prison chief has apologised for the deaths of more than 14,000 people at S-21 prison.

Kaing Guek Eav, also known as Duch, is the first of Pol Pot's officials to accept blame for crimes committed by the regime 30 years ago.

'I am responsible for the crimes committed at S-21, especially the torture and execution of the people there,' he told a UN-Cambodian court where he is charged with crimes against humanity and war crimes.

'May I be permitted to apologise to the survivors of the regime and families of the victims who had loved ones who died brutally at S-21. I would like you to forgive me,' he told the panel of five judges.

Now a born-again Christian, he said he would like to express regret and sorrow for all the crimes he committed during the 1975-79 reign of terror in which 1.7m people died in Cambodia.

But the 66-year-old former maths teacher said he was only following orders issued by the top Khmer Rouge leadership, and had feared for the lives of his family if he had disobeyed.

'I am solely responsible for this crime, but I am just a scapegoat. A person who played a role in the killings,' he told the court on the second day of his trial.