A senior Cambodian official says he expects a United Nations-backed court to begin trying as many as 10 former Khmer Rouge leaders for war crimes before the end of next year.

Deputy Prime Minister Sok An says he believes there are no more obstacles to block the trials, after Cambodia's parliament approved a series of constitutional amendments needed for the tribunals to take place.

Monday, lawmakers ratified Cambodia's 2003 agreement with the United Nations that set up the tribunal.

Details of funding remain to be settled. Cambodian Prime Minister Hun Sen has said Phnom Penh can provide security, utilities and facilities, but would be unable to pay other costs, which reportedly could amount to as much as $50 million.

Under Khmer Rouge rule from 1975 to 1979, an estimated two million Cambodians were killed or died of starvation, disease and overwork.