Cambodia's UN-backed war crimes court Thursday promised a "fair and just" verdict in the trial of Khmer Rouge prison chief Duch, after days of emotional testimony from the relatives of victims.

Jail supremo Duch (66) is on trial before the Extraordinary Chambers in the Courts of Cambodia (ECCC) for overseeing the torture and execution of roughly 15,000 people at the notorious Tuol Sleng detention centre during the hardline communist regime's 1975-79 rule.

Several foreigners and Cambodians have come to the court in Phnom Pehn in recent weeks to testify about the effects on their lives of losing loved ones in the prison-turned high school.

Head judge Nil Nonn warned them on Thursday to only give evidence and not to use the hearing "to take revenge", after some witnesses spoke out harshly against Duch.

"At the end, the chamber would consider all this information and evidence, and then we would issue a judgement which is fair and just and is acceptable by all the parties to the proceedings," Nil Nonn added.

New Zealand Olympic rower Rob Hamill, whose brother Kerry was murdered by the Khmer Rouge after his yacht was blown off course and into Cambodian waters, told the court on Monday how he had sometimes felt like killing Duch himself.

Court officials have said Duch's trial is expected to wrap up in October, with the judges likely to issue a verdict some months later.

Duch, a former maths teacher whose real name is Kaing Guek Eav, has previously accepted responsibility for his role in governing the jail under the regime and begged forgiveness from the families of the victims.

The jail chief last week asked for the "strictest level of punishment" -- even death by stoning -- for his crimes against the Cambodian people.

But he has denied that he played a leading role in the Khmer Rouge's hierarchy, saying that he obeyed orders from the top because he feared for his own and his family's lives.

Led by Pol Pot, who died in 1998, the Khmer Rouge emptied Cambodia's cities in a bid to forge an agrarian utopia, resulting in the deaths of up to two million people from starvation, overwork and torture.

(Source: AFP)
(Photo: Extraordinary Chambers in the Courts of Cambodia on Flickr)