Sudan will co-operate with UN and African Union peacekeepers in Darfur, Sudan's UN ambassador said after the UN Security Council backed a joint force.

The mandate for the 26,000-strong force was watered down to appease critics and it will only be able to protect civilians deemed to be under threat.

The new UN-AU mission head welcomed the move but urged a political solution "as there needs to be a peace to keep".

The warring factions in the four-year conflict are due to meet on Friday.

Since rebel groups rose up against the Khartoum government's rule in 2003, at least 200,000 people are thought to have died in the region and more than 2m have fled their homes.

Sudan's government and pro-government Arab militias are accused of war crimes against the region's black African population, although the UN has stopped short of calling it genocide.

'Without prejudice'

Darfur's rebel groups have long sought UN peacekeepers and have hailed the resolution

"We very much welcome the UN troops in Darfur any time, without any condition," Sudan Liberation Army commander Abu Jamal Khalil Ali told the BBC.

Abu Elgasim, field commander for a different SLA faction, also welcomed the UN resolution.

The first peacekeeping troops are due to begin arriving in October.

"We will be committed, we will be faithful and honest to our obligations," Sudan's ambassador to the UN Abdalmahmood Abdalhaleem Mohamad told the BBC.

However, he also warned that the resolution was not a "blank cheque" for the peacekeepers.

The resolution says they can use force "to protect civilians without prejudice to the responsibility of the government of Sudan".

Head of the UN-AU hybrid mission Rodolphe Adada told the BBC the force would be one of "two legs for finding peace in Darfur".

"I'm sure it will be one of the main tools for forwarding peace in Darfur, but it's only a peace operation, you need to have peace to keep," he told the BBC's Network Africa program.

"This is why the political meeting is of the essence."

The mission, to be known as Unamid - the United Nations African Union Mission in Darfur - is expected to cost up to $2bn  a year and will be world's largest peacekeeping force.

Mr Adada said the force will mainly be drawn from African countries, a move also hoped to appease Sudan's initial antagonism to the force.

But the resolution says the UN has overall command of the force.

'Disappointed'

UN Secretary General Ban Ki-moon described the mission as "historic and unprecedented".

Humanitarian workers hope the new force will provide security for them to be deliver aid to civilians.

"It is very clear that the humanitarian situation in Darfur is deteriorating, so we're hopeful that we can get back to a situation where we can just get on with our work," Sarah Smith from aid agency Goal told the BBC.

Jonathan Pearce, from the UK's Disasters Emergency Committee, said the peacekeeping force could make a "tremendous impact".

But Democrat Russ Feingold, who chairs the US Senate foreign relations sub-committee on Africa, said: "I am very disappointed that the resolution's co-sponsors have succumbed to pressure from the Sudanese government."

The new force will not have the right to disarm the militias and it does not have the powers to pursue and arrest suspected war criminals indicted by the International Criminal Court.

Furthermore, the resolution does not threaten sanctions against Sudan if it does not comply.

The unanimous vote came after negotiations secured the support of China, which has a veto on the Security Council and strong economic interests in Sudan.

The joint African Union-UN meeting in Arusha, Tanzania, is to try later this week to establish a framework for peace talks between the Darfur rebels and Sudanese government.

One of the numerous rebel groups signed a peace deal last year but the violence has continued.

PHOTO CAPTION

African Union soldiers in Darfur (file pic)