The United Nations (UN) is short of aviation, transport and logistic personnel necessary for the functioning of a new force of up to 26 000 troops and police in Sudan's Darfur region, according to a report issued on Thursday.

UN Secretary-General Ban Ki-moon, who issued the report, said the August 31 deadline for troop contributors would have to be extended because "offers are still lacking for some critical military capabilities."

The Security Council, which requested the report, authorized the joint African Union (AU)-UN force last month to protect civilians from fighting that has driven 2,5-million people from their homes over the last four years. About 200 000 are estimated to have died.

On Thursday, Darfur rebels accused the government of bombing South Darfur in the latest aerial attack that has resulted in more than 20 000 people fleeing their homes in August alone. Ban's report put the number at 25 000 when other violence was included.

Infantry troops, mainly from Africa, for the Darfur force have been offered in sufficient numbers but some contingents lack "the equipment necessary to implement their required tasks," the secretary-general said.

And Ban said there had been enough offers for the more than 6,000 civilian police requested, but most of them came from a few countries. Peacekeeping officials were searching for a more "diverse police component," he wrote.

VISAS AND OVERFLIGHTS

Ban also asked Khartoum to speed up granting visas for visits by troop and police contributors and lift the limit of overflights and aircraft allowed to land in Darfur "in order to facilitate the timely deployment of UNAMID," the UN-AU Mission in Darfur.

"I call on member states to urgently provide the outstanding military contributions that are critical for UNAMID to fulfill its challenging mandate," he wrote.

The secretary-general is traveling to Khartoum, Darfur and Juba in Sudan next week to smooth the way for the peacekeeping force as well as push for a new peace agreement between the government and a myriad of rebel groups. He also goes to Chad and ends his trip in Libya.

Ban said that setting up preparations for the force, which would absorb or replace the 7 000 under-financed and under-equipped African Union troops now in Darfur, was "enormously complex" in the poor, arid region with little infrastructure.

He said he was deeply concerned about the escalation of violence, including clashes between two rebels tribes that resulted in 100 civilian deaths, and a rebel attack on local police that killed 20 policemen.

Ban said it was unacceptable that Sudanese police on August 21 had barred UN. and AU officials from visiting the Kalmar camp for uprooted civilians in South Darfur.

"I appeal to the government of Sudan and to all parties to refrain from military action and work towards creating a climate conducive to the envisaged (peace) negotiations," Ban said.

Ban, during his trip to Juba in southern Sudan, aims to bolster a fragile peace agreement that ended a 21-year-old war between the Muslim-dominated Khartoum government and the Christian and animist south.

He has called on the Sudanese army to get its troops out of the south after a July 9 deadline was missed for the formation of joint units.