Cambodia's prime minister, Hun Sen, has criticized the United Nations for withdrawing support for a war-crimes tribunal to try leaders of the Khmer Rouge.

The prime minister criticized the United Nations' announcement that it was pulling out of negotiations to set up a joint court to try former Khmer Rouge leaders.

Speaking to reporters after a meeting with Burmese diplomats, Mr. Hun Sen called the move the latest U.N. folly in dealing with the impoverished nation. Mr. Hun Sen referred to the United Nations' recognition of the Khmer Rouge as the legitimate government when it ruled Cambodia from 1975 to 1979.

The United Nations announced its decision Friday after four and a half years of negotiations. U.N. leaders criticized the government's lack of urgency on the issue, and its insistence that Cambodia's tribunal law, which was passed last August, have ultimate control over the process. The United Nations said it decided that Cambodia's tribunal law could not guarantee the independence, impartiality and objectivity of a joint court.

The Cambodian prime minister promised to wait one or two months, so that U.N. members who were unhappy with what some diplomats called a "unilateral" decision, could urge the world body to reconsider its position. But Mr. Hun Sen stressed that he would not wait longer, and emphasized the need for the Khmer Rouge leaders to be brought to justice.

Mr. Hun Sen also said he plans to ask the national assembly to extend the detention period for two top Khmer Rouge leaders.

Commander Ta Mok, and the former director of the infamous "S-21" prison, Kang Kek Ieu, known as Duch, are the only former Khmer Rouge members in prison. They have been charged with crimes related to the radical communist movement's brutal government, which is blamed for the deaths of more than one million people. Their legal detention period expires in a few months.