In his monthly briefing on Sudan to the UN Security Council, Annan said the descent into lawlessness by the region's armed movements, violence against humanitarian workers and unprecedented criminality in Nyala, the capital of South Darfur, was a dangerous pattern that demanded "urgent corrective action".

"While the daily rate of casualties from fighting has declined in recent months, the damage to the social and economic fabric in Darfur and the longer-term costs of this conflict are steadily becoming clearer," Annan said in a reort released on Thursday.

He said some 3.2 million people in the region were in need of assistance, while the number of internally displaced persons (IDPs) had remained at approximately 1.9 million. Insecurity in IDP camps in western Darfur, he added, was of major concern, with violent attacks on humanitarian workers organised by local sheikhs attempting to manipulate the ration card system.

He called for the African Union (AU) Mission in Sudan to be brought to full strength and full operational capacity as soon as possible, and noted that there were indications that the presence of the AU and its patrols had directly resulted in a decrease in both sexual and gender-based violence and other human rights violations.

The AU has reported a shortfall of some US $173 million to fund its operations in Darfur; an AU official told IRIN on Thursday that the body could soon fail to pay its' troops salaries unless money was found.

"I have written to major partners of AU to urge them to fill the funding gap identified by AU," Annan said.