Cambodia's Prime Minister Hun Sen has agreed to work with the United Nations to revive plans to establish a tribunal to try former Khmer Rouge leaders for crimes including genocide.

The UN suspended four-and-a-half years of negotiations on the issue in February after deciding that a joint tribunal with Cambodia's judicial system was unlikely to succeed.

Right now, the door is beginning to open, but the problem is whether the Security Council or the General Assembly will give the mandate

Prime Minister Hun Sen

But on Tuesday, UN Secretary General Kofi Annan tried to break the impasse by offering to resume talks, providing he receives a mandate from the UN Security Council or General Assembly.

The UN wants former Khmer Rouge leaders to be brought to trial for atrocities carried out by the regime between 1975 and 1979 in which 1.7 million people died.

Close co-operation

Hun Sen urged both the UN and his government to work closely together to finally bring about the establishment of a tribunal.

"Everything is already at a good point but we have to try to join together, not only Cambodia but also the secretary general and other countries that are involved," Hun Sen said.

"Right now, the door is beginning to open, but the problem is whether the Security Council or the General Assembly will give the mandate," he added.

Pol Pot oversaw the genocide

Experts say that it should be possible to gain a mandate from the UN General Assembly, but that China, a permanent member of the Security Council could veto a trial.

China supported the Khmer Rouge, but maintains that any crimes against humanity carried out by the regime remain a domestic matter.

Previous negotiations between the UN and Cambodia collapsed because of Cambodia's insistence that national law would take precedence over the agreement with the UN in the trials.

There was also disagreement about who should go on trial - Cambodia wants to restrict prosecution to about 10 selected Khmer Rouge figures.

Evading justice

Hun Sen has said that the if the focus of the tribunal is too wide it may reignite the country's civil war which ended in 1998.

The problem is compounded by the fact that many Khmer Rouge leaders defected to the government's ranks at the end of the war.

No Khmer Rouge leader has ever faced trial for the "killing fields" atrocities carried out when they were in power.

The extreme Maoist group seized control of Cambodia in 1975 and about 1.7 million people are believed to have died during their reign of terror through execution, torture, starvation and hard labour.