PHNOM PENH - The head of state under Cambodia's Khmer Rouge, Khieu Samphan, appealed to be released from detention Friday ahead of his trial at the UN-backed war crimes court.

Khieu Samphan, 77, is charged with crimes against humanity and war crimes but is seeking to be freed on bail from the purpose-built detention centre at the court.

"I can tell you that (Khieu Samphan) is not going to flee. The reason that he could be released is so that he can grow vegetables or do a bit of gardening for his own use," Cambodian co-defence lawyer Sa Sovan told the court.

Sa Sovan said there was no evidence his client would pressure witnesses if released or be attacked by Khmer Rouge victims seeking revenge.

But prosecutor Yet Chakriya said there was no guarantee letting Khieu Samphan out of jail would not disrupt public order, and cited a 1991 incident where he was attacked by a mob in the Cambodian capital Phnom Penh.

"A huge number of people surrounded him and threw rocks at him. It was only on the intervention by the government that Khieu Samphan escaped," Yet Chakriya said.

Khieu Samphan's other lawyer, famed attorney Jacques Verges attempted to raise the allegations that Cambodian tribunal staff were forced to pay kickbacks for their jobs.

Australian judge Rowan Downing, however, told him that it was not possible to talk about "a new issue" during proceedings in which he was supposed to be responding to prosecution arguments.

"If you believe we should not talk about corruption here, I shall not impose such a debate upon you," Verges responded.

"I shall also remain silent because the head of this state has publicly said he wanted this chamber to be brought to a conclusion. In this sense, you are moral squatters," Verges said.

His comments were a reference to remarks by Cambodian Prime Minister Hun Sen earlier this week in which he said he would rather the UN-backed court failed than pursue more suspects for prosecution.

Frenchman Verges, who has acted for some of the world's most infamous figures including Nazi war criminal Klaus Barbie and Venezuelan terrorist "Carlos the Jackal," is known for attempting to sew confusion in the courtroom.

A fierce anti-colonialist, Verges, who was born in Thailand, reportedly befriended Khieu Samphan and other future Khmer Rouge leaders while at university in Paris in the 1950s.

The court is expected in the next few month to make a decision on whether to release the former leader.

Khieu Samphan's appeal comes in the same week two other suspects from the 1975-1979 regime also sought to be released from the detention centre.

Former foreign minister Ieng Sary on Thursday appealed to be released ahead of his trial on the grounds jail was affecting his health. The regime's prison chief, Duch, also sought to be released.

While Duch's trial is under way, no date has been set for the trials of Khieu Samphan, Ieng Sary and two other Khmer Rouge leaders held by the court.

Up to two million people were executed or died of starvation and overwork as the Khmer Rouge regime emptied Cambodia's cities, exiling the population to vast collective farms in its bid for a communist utopia.

Khmer Rouge leader Pol Pot died in 1998. The court also plans to prosecute Ieng Sary's wife Ieng Thirith, who was the regime's minister of social affairs and former Khmer Rouge ideologue Nuon Chea.