Phnom Penh - The chief international prosecutor for Cambodia's Khmer Rouge tribunal said Monday, one day ahead of the opening hearing, that it would be a highly technical but "hugely significant" event.

Co-prosecutor Robert Petit said although the initial trial hearing of former Tuol Sleng torture facility chairman Kaing Guek Eav, known by his revolutionary name Duch, would be a procedural affair, it would be a milestone for the UN-backed tribunal.

"The fact this is the beginning of the first trial is in itself highly significant," he said, "but it will also demonstrate the complex task the court has ahead of it and the capacity of the court to carry out this task."

Duch, 67, will not be called to testify during the hearing, but the court is to choose witnesses and set a date for the trial's next stage.

The born-again Christian and former mathematics teacher is the first of five detained former Khmer Rouge leaders to face trial for crimes against humanity.

Duch has been detained since 1999 and is the only former leader to have admitted guilt for his crimes.

Up to 2 million people - or a quarter of Cambodia's population at the time - died from starvation, overwork or exhaustion during the ultra-Maoist group's rule from 1975 to 1979.

Petit refuted suggestions that recent conflict between international and Cambodian prosecutors over the scope of the investigation would inhibit the court's ability to put Duch on trial.

International prosecutors have argued that the court should investigate more former Khmer Rouge leaders while the Cambodian side has maintained the current five is enough.

"This disagreement is not a reflection on how the prosecution has worked together nor its impact on how the trial will progress," he said.

More than 1,000 members of the public and media were expected to attend Tuesday's hearing in Phnom Penh.

Tribunal spokeswoman Helen Jarvis said the court's facilities were prepared to accommodate the large number of attendees but confirmed that members of the public would be turned away if the 504-seat public gallery is filled.

"We have received hundreds of registrations from national and international media, but the tribunal has anticipated this kind of interest and it is prepared," she said.

"The court has the largest public gallery in the world," she added, "so we will be able to provide enough seating for Cambodians to witness this historically significant event." (dpa)