But as a United Nations-backed tribunal prepares to hold its first trial session next month, it is embroiled in a wrangle over numbers that goes to the heart of longstanding concerns about the tribunal's fairness and independence.

The Cambodian government, critics say, is attempting to limit the scope of the trials for its own political reasons, a limit that the critics say would compromise justice and could discredit the entire process.

The first defendant is the man with perhaps the most horrifying record: Kaing Guek Eav, known as Duch, the commander of the Tuol Sleng torture house in Phnom Penh, where at least 14,000 people were sent to their deaths. His trial is to open with a procedural hearing, set for Feb. 17, at which more substantive sessions, involving witnesses and evidence, are expected to be scheduled.

Four other defendants, all of whom were members of the Khmer Rouge Central Committee, are also in custody, waiting their turns to face charges in crimes that occurred while they were at the top of the chain of command from 1975 to 1979. As much as one-fourth of the population died from disease, hunger, overwork or execution under the Khmer Rouge's brutal Communist rule.

Those five defendants are enough, Cambodian officials say.

But foreign legal experts counter that within reasonable limits, the judicial process should not be arbitrarily limited.

After a decade of difficult and not always friendly negotiations between the United Nations and the Cambodians, a hybrid tribunal is in place, with Cambodian and foreign co-prosecutors and panels of co-judges in an awkward political and legal balancing act. Now, even before Duch's trial gets under way, that balance is being tested.

Last month the foreign co-prosecutor, a Canadian named Robert Petit, submitted six more names to the court for investigation, saying that he had gathered enough evidence to support possible charges. Petit's Cambodian counterpart, Chea Leang, objected - not on legal grounds, but for reasons that appear to reflect the government's position on the trials.

Additional indictments, the Cambodian prosecutor said, could be destabilizing and would cost too much and take too long and would violate the spirit of the tribunal, which she said envisioned "only a small number of trials."