Jan Pronk gave his most pessimistic assessment yet to the U.N. Security Council on Friday. He said marauding Arab militia were succeeding in their ethnic cleansing campaign, erasing village after village.

"Looking back at three years of killings and cleansing in Darfur we must admit that our peace strategy so far has failed," Pronk said. "All we did was picking up the pieces and muddling through, doing too little too late."

"At least once a month groups of 500 to 1000 militia on camel and horseback attack villages, killing dozens of people and terrorizing the others who flee away," Pronk said.

The United Nations is contemplating a peacekeeping force in Darfur, where the African Union has fielded a force of 7,000 with a limited mandate and scarce funds. But U.N. peacekeeping officials have not planned for the high numbers of troops Pronk suggested.

The Darfur conflict erupted into violence in early 2003 when African tribes took up arms accusing the Arab-dominated Khartoum government of neglect. The government retaliated by arming Arab militia, known as Janjaweed, who began a campaign of murder, rape, arson and plunder and drove villagers into squalid camps. Khartoum denies the charge.

Pronk proposed sophisticated mobile units able to deter attacks on civilians and disarm militias. U.N. Secretary General Kofi Annan said on Thursday he hoped the United States and European nations would help.

In addition, Pronk said there had to be soldiers available to protect uprooted civilians or they would not "dare to return" to their villages.

The African Union and Security Council members have accepted "in principle" of the need for a transfer to a U.N. peacekeeping force "at some point," Security Council President Augustine Mahiga of Tanzania told reporters. The AU would not make a final decision until March, he said.

Sudan so far has rejected any troops other than the African Union's. "Naturally what should happen is to give them the money they want, not to complicate matters by involving another force on the ground," Foreign Minister Lam Akol told Reuters in Khartoum.

But Pronk played this down and said Khartoum had previously overcome initial objections to other steps to ease the conflict.

He also said talks in Abuja, Nigeria, between Darfur rebel groups would take another year or two unless security arrangements were completed first, followed by talks on power and wealth sharing. The rebels, he said, were "fighters not thinkers."

A stalled second security forum included Chad, itself involved in border clashes with Sudan, as a co-chairman.

For more than a year, the Security Council has dealt with the warfare in Sudan's western region. It has imposed an arms embargo, which all sides have violated.

It also voted last March to put an asset freeze and travel ban on belligerents, which has yet to be imposed, partly because of objections from Qatar and China. It has referred the crisis to the International Criminal Court last March but Pronk said the tribunal was working too slowly.