PHNOM PENH, Feb 21 (Reuters) - The European Union is calling on Cambodia to come up with more cash for a Khmer Rouge war crimes tribunal, where resignations have slowed proceedings and some staff are threatening to strike after going for more than two months without pay.
Up to 2.2 million people died under the ultra-Maoist Khmer Rouge regime from 1975 to 1979, a quarter of the population. The tribunal, set up in 2005, has found only one person, a relatively lowly prison chief, guilty of crimes connected with the killings.
Under the agreement for the U.N.-backed tribunal, the United Nations was to pay for international staff and operations, while Cambodia paid for the national side, but the government has been repeatedly criticised for a lack of support.
"The EU keeps encouraging the Royal Government of Cambodia to continue substantially increasing its own contribution to the tribunal, as a sound measure to improve its sustainability and its ownership by Cambodia itself," EU Ambassador Jean-Francois Cautain said in an email to Reuters.
Pol Pot, the architect of the "Year Zero" revolution, died in 1998, but three of his closest comrades are now on trial for murder and crimes against humanity, among a litany of charges.
The funding difficulties have put a spotlight on the government's commitment to the process.
It has been accused of interfering behind the scenes to put the brakes on the court and limit the scope of investigations that could implicate powerful political figures.
Prime Minister Hun Sen, himself a former Khmer Rouge guerrilla who defected to the regime's eventual conquerors, Vietnam, has said he would not allow any new indictments and that he would be happy if the United Nations packed up and left.
Two international judges quit within six months in 2011 and 2012 complaining of political interference, and many Cambodians fear the defendants in the court's second case - "Brother Number Two" Nuon Chea, a former foreign minister, Ieng Sary, and ex-president Khieu Samphan - may not live to hear a verdict.
The EU, the second-biggest donor at the court after Japan, was holding back a 300,000 euro ($401,000) grant until "the contractual obligations of the grant agreement are fully met", Cautain said.
About 270 Cambodians have not been paid since November and are working at the court without contracts.
The EU also wants to see a reduction in the running costs of the Cambodian side of the Extraordinary Chambers in the Court of Cambodia, as the tribunal is known, after a 20 percent cut in the international budget in 2013, Cautain said.
The government says it has committed $1.8 million for this year to pay for utilities, security, healthcare and transport, as well as the courthouse, which it owns.
Government spokesman Ek Tha pointed out that "exceeds the commitment from the national budget to the country's Supreme Court by 257 percent and to the Appeals Court by 300 percent".
The government has used outside contributions to pay the estimated $9.3 million a year wage bill for Cambodian staff.
The only conviction to date is that of Kaing Guek Eav, better known as Duch, sentenced to life imprisonment for deaths at the notorious Tuol Sleng prison in Phnom Penh that he ran. ($1 = 0.7479 euros) (Reporting by Prak Chan Thul; Editing by Alan Raybould and Robert Birsel)