In the first major decision for the Khmer Rouge tribunal, judges denied Monday the pre-trial release of former prison chief Duch, accepting the arguments of prosecutors he could flee or be harmed by potential witnesses or family of victims.

With Duch, whose real name is Kaing Khek Iev, in the dock less than an hour, the judges of the Pre-Trial Chamber said they were upholding his detention.

The decision follows a public hearing in November where Duch appealed to be released ahead of an atrocity crimes trial next year. Duch oversaw Tuol Sleng prison, where as many as 16,000 Cambodians were tortured and later executed. He was detained without trial by the military courts for eight years until July, when he was turned over to the tribunal.

Judge Prak Kimsan, head of tribunal's Pre-Trial Chamber, said the judges had unanimously decided to hold Duch ahead of trial.

Duch lawyer Francois Roux said through an interpreter he was disappointed at the decision, but at least one Tuol Sleng survivor, Chum Manh, said he supported the ruling.

"I think that the tribunal is proper, because we are deeply hurt," said Thong Phan, a resident of Kandal province who attended the hearing. "With the tribunal to prosecute, I am happy."

"It is a good thing that Duch's case has been processed ahead of the four other cases, because Duch's case is the most difficult, since he has been in provisional detention for eight years," said Hisham Mousar, a legal expert for the rights group Adhoc.

A total five former leaders are in the tribunal jail awaiting trial, including chief ideologue Nuon Chea.

"We can see that other cases, such as Nuon Chea, who has appealed formally to the tribunal, are easier to process than this case," Hisham Mousar said.