Ed Royce, a House Republican from California, said the UN-backed tribunal in Phnom Penh has cost millions of dollars, tried only one man, and was leaving Cambodians in America frustrated by its lack of effectiveness.

“There is an expression used in the US, ‘Justice delayed is justice denied,’” he said in an e-mail Friday. “I’m afraid that may be the case in Cambodia.”

The court has come under increased criticism for its handling of the cases against Khmer Rouge leaders, including from victims groups in the US and Cambodia.

“This is very slow progress for a court that is eight years old and has received hundreds of millions of dollars in funding from the international community,” Royce wrote in response to questions. “The US Congress has expressed its concern over the corruption and mismanagement. Unfortunately, the court is also suffering from political interference at the highest levels.”

Royce was referring to allegations that surfaced on the Cambodian side of the court, when staff complained they were paying kickbacks to keep their jobs. Prime Minister Hun Sen has publicly opposed the prosecution of two more cases at the court, while top ruling party officials have refused to comply with summonses there.

The tribunal has spent around $150 million since 2003, and only stood up in 2006, after much wrangling between Cambodian officials and the UN. In June 2010, it sentenced Duch, the former head of Tuol Sleng prison, to a commuted 19 years in prison, after a lengthy trial. That case is currently under appeal. A second case, for top leaders Nuon Chea, Khieu Samphan, Ieng Sary and Ieng Thirith, will begin in full later this year. Two more cases that would require more indictments have stalled in the court process.

Royce, who is a House member of the committees of Financial Services and of Foreign Affairs, said the Khmer Rouge was responsible for the deaths of up to 2 million Cambodians, giving survivors a desire to hold its leaders accountable.

“This horrendous crime was committed against the Cambodian people, but we all have an interest in seeing that justice is done,” he wrote.

Tribunal spokesman Huy Vannak said this week that an independent audit had cleared the court of corruption charges, but he acknowledged there have been complaints over the slow work of the tribunal as well as allegations of political influence.

But he said the court process was actually moving faster than other war crimes tribunals, while at the same time jurists are working to ensure that the process is legitimate.

“If we are careless, then such a heritage will return,” he said.

Still, Royce said, Cambodians in the US are not happy with the way the trials have gone.

“Most Cambodian-Americans I’ve talked to express frustration that the tribunal is not open to the public and that there aren’t more defendants on trial, including officials in the current government,” he said.

Huy Vannak said the court was working 30 years after the fall of the regime, making some indictments impossible.

“We also know that senior Khmer Rouge leaders like Pol Pot, Ke Pauk, Son Sen and Ta Mok died,” he said. Had they lived, they could have been included in the first two trials at the court, he said.