The setting up of a tribunal has faced years of delays

Enough money has been received from international donors to fund work at the court for a "sustained period of time", the UN said in a statement.

The Communist regime which ruled from 1975-79 is blamed for the deaths of more than one million people out of an eight million-strong population.

Cambodia first sought UN funding for the court eight years ago.

UN Secretary-General Kofi Annan urged the Cambodian to move fast now that the money is in place.

Still free

There are concerns that the ageing top figures of the murderous regime, who have never been prosecuted, might die before being taken to court.

Observers expect the first trials to begin by next year.

The regime, headed by Pol Pot, persecuted its political opponents as well as minority groups.

They allowed food shortages to kill people by starvation, while others were forced to move from the cities to the countryside, where they died from overwork in labour camps.

Pol Pot died in 1998, and only two of his six to 10 former top lieutenants are currently in jail.

The Cambodian government and the UN had agreed that the setting up of the court could start once pledges sufficient to cover the body's work for the next three years had been received.

At a donor's conference last month, UN members pledged a total $38m, $21.6m of which came from Japan.

Cambodia has allocated $13m.

Cambodians have never really confronted the horrors of the Khmer Rouge, the BBC's Asia correspondent, Andrew Harding, reports.

Some observers have questioned whether an expensive tribunal is the answer or whether a broader approach, like South Africa's Truth and Reconciliation Commission, would serve Cambodians better.