PHNOM PENH, Cambodia (CNN) -- A joint Cambodian-United Nations court, currently trying five former members of the ultra-Maoist Khmer Rouge group on war crimes charges, is itself facing allegations of corruption and bribery.
Cambodia's Minister of Information Khieu Kanharith says no proof of kickbacks or corruption has been found.
Two employees of the court's Office of Administration told CNN of an ongoing kickback scheme involving Cambodian staff. The staffers asked their identities be protected out of fear of retribution to themselves and their families.
"We are talking about 30 to 40 or even a little bit more ... a month," said one employee, referring to the total amount allegedly taken from employees. "Thousand dollars. Thirty or 40,000 dollars a month."
Cambodian staff at the office, they say, are forced to hand the money over -- a chunk of their salaries -- and the funds go to an official.
"They are supposed to pay a certain amount (of) money -- a certain percentage," the employee said. "So every month, they have to put it in an envelope -- and give it to ... each section has one person go around to collect it ... the money is in cash, in U.S. dollars."
There is no suggestion that the court's judges or lawyers -- who are hearing and presenting the case against the former Khmer Rouge leaders -- are involved in the alleged corruption.
The Cambodian government told CNN a senior Cambodian court official was investigated for corruption, but was exonerated. "They told me they cannot find any proof of kick-back or corruption," said Khieu Kanharith, government information minister. "If you want the court -- the trial -- to go ahead, separate the two cases."
However, a defense attorney for one of the defendants said the trial and the allegations of corruption are inextricably linked.
"What's really disturbing is that by the time the judges make their decision, every piece of evidence, every bit that they look at and evaluate and deliberate on, will have passed through the office of administration and will have literally passed through the hands of people who we say have dirty hands," said Andrew Ianuzzi, a consultant for defendant Nuon Chea's legal team.
Defense attorneys say they plan to bring up the corruption allegations during the trial in an effort to discredit the court.
The Cambodian government refused United Nations requests for an independent international war crimes trial for the Khmer Rouge defendants, agreeing only to a joint trial where the government participates along with the international judges. Watch a report on the trial a Khmer Rouge torture camp commandant »
Prosecutors are attempting to prove that the five defendants played a significant role in the deaths of as many as two million Cambodians during Khmer Rouge rule of the country from 1975 to 1979. The trial has already cost $56 million, more than $10 million per defendant.
But the court has asked for another $50 million to carry it through the end of 2009. The total could go higher if the trial continues into 2010.
The United Nations says its internal affairs body -- the Office of Internal Oversight Services (OIOS) -- is investigating the corruption allegations within the court, but won't elaborate.
"This matter has been under investigation by OIOS, whose work is confidential," the United Nations said in a statement. "The result of the probe will be submitted to the Cambodian government for further action."
In a letter sent to attorneys for the trial defendants, Sean Visoth, the head of the court's Office of Administration, writes that his office has "never tolerated any kind of corruption or malpractice." Visoth says the court now has an anonymous "complaint mechanism" in place.
Meanwhile, however, independent trial monitors say they believe a culture of fear prevents other current and employees from coming forward.
"At the court, I have heard people express concerns about loss of their job, repercussions or retaliations against their families, and also some possibility of physical fears," said Heather Ryan, a Khmer Rouge trial monitor.
The employees spoke out, saying they were fully aware of the risk.
"To me, it is really sick. How can you take money from people each month and look people in the eye and say, 'Oh, I don't know anything about it?'" one employee asked.