The Khmer Rouge prison chief blamed for thousands of deaths at an infamous torture centre asked Cambodia's genocide tribunal to release him yesterday, saying he had already spent 10 years in jail awaiting trial.

The request by Kaing Guek Eav, also known as Duch, stunned the courtroom and raised doubts about the sincerity of his earlier remarks to the panel accepting responsibility for his prison role, asking forgiveness from victims' families and expressing readiness to accept heavy punishment.

Judges declined to act on Duch's request before ending the trial's proceedings, following several days of closing arguments.

They did not announce a date for their ruling, which is expected early next year.

Duch commanded the notorious S-21 prison where those accused of disloyalty to the xenophobic communist regime were held. He oversaw the torture and execution of about 16,000 men, women and children during the Khmer Rouge's reign.

Duch said he had fully co-operated with the tribunal and had been detained since 1999.

He has denied personally killing or torturing the S-21 prisoners, and said he felt compelled by fear for his own life to follow the orders of senior Khmer Rouge leaders.