Sudanese President Omar al-Bashir has agreed unconditionally to a joint UN-African Union peacekeeping force for Darfur, diplomats have said.

South Africa's ambassador at the UN, Dumisani Kumalo, said Mr Bashir backed the move after a meeting with Security Council envoys in Khartoum.

Sudan agreed to allow the 19,000-strong force earlier in the week but ultimate control has been a sticking-point.

Violence in Darfur has killed more than 200,000 people and made 2.5m refugees.

An existing AU force of 7,000 troops has struggled to contain the conflict.

Much of the violence has been linked to clashes between government-sponsored Janjaweed militias and Darfur's rebel groups.

Diplomats' caution

Mr Kumalo said that, in two hours of talks, Mr Bashir had not raised any objections to the deployment of the joint force.

He said he expected the Security Council to recommend within a month that the UN General Assembly fund the force.

The UN would retain overall control, diplomats said.

"Command and control processes will be those of the United Nations," UK ambassador Emyr Jones Parry said, quoted by Reuters news agency.

"And that is necessary if indeed this operation is to be funded from the peacekeeping budget of the United Nations."

The joint contingent policing Darfur will number between 17,000 and 19,000 soldiers.

Plans envisage the UN taking overall control of the peacekeeping mission, with AU troops performing much of the day-to-day work.

However, diplomats continue to caution that Sudan has a history of making agreements and then raising difficulties.

BBC UN correspondent Laura Trevelyan in Khartoum says that even if everything goes smoothly from now on, it will be 2008 at the earliest before this force is deployed in Darfur.

The US and UK have warned that Sudan could face UN Security Council sanctions if it continues to resist the deployment of peacekeepers.

Oxfam leaves

British aid agency Oxfam has meanwhile announced it is withdrawing permanently from Gereida in Darfur.

The agency said it was leaving because of concerns over the safety of its workers.

Three aid agency bases in Gereida were attacked by a rebel group in December. One aid worker was beaten, another was raped and several were subjected to mock executions.

Oxfam said it was withdrawing because no action had been taken to punish the perpetrators of the attacks, stolen assets had not been returned and there were no "credible assurances" that a similar attack would not happen again.

The charity has been providing water, sanitation and healthcare to some 130,000 people in camps outside Gereida town, reports say.

Separately, UN Secretary-General Ban ki-Moon has said climate change is partly to blame for the conflict in Darfur.

Declining rainfall, caused in part by climate change, had made arable land scarce and forced a confrontation between rival ethnic groups in Darfur, Mr Ban wrote in an editorial for US daily, The Washington Post.

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Sudanese President Omar al-Bashir