KHARTOUM (AFP) - Suspected Janjaweed militia have ambushed the beleaguered UN mission in Sudan's war-torn Darfur region, with one peacekeeper confirmed dead and another six missing, an official said on Wednesday.

The attackers ambushed the UNAMID convoy on Tuesday at Um Hakibah in North Darfur State, southwest of the peacekeeping mission's headquarters in El Fasher, said the UNAMID official speaking on condition of anonymity.

"One is confirmed dead and six are missing. The location of the incident is Um Hakibah, 100 kilometres (60 miles) from Shangil Tobayi," the official said.

An unknown number of people have been flown back for medical treatment in El Fasher, the official added.

The peacekeepers were attacked while returning from following up allegations by the Minni Minnawi faction of the Sudan Liberation Army, which signed a 2006 peace deal with the government, that two of the former rebels had been killed.

"It looks like it was a big attack. They were taken on by what sounds like a very large force," said the official.

UNAMID deputy force commander Karenzi Karake was on the ground on Thursday assessing the situation and further details of the attack were expected upon his return.

UNAMID troops have been subject to a string of attacks in the six months since the UN-led mission assumed control from an African Union force.

Tuesday's attack is the latest in a series of assaults on UNAMID across the vast region of Darfur, where ethnic and tribal conflict has spiralled into escalating insecurity and banditry over the past five years.

Last month, Arab militia briefly abducted and physically assaulted a UN official and three colleagues held at gunpoint during a standoff near the main UNAMID military base in El Geneina, the capital of West Darfur.

In late May, dozens of heavily armed men on horseback ambushed a UNAMID patrol in Darfur and seized weapons from Nigerian troops near El Geneina, and in a separate incident a Ugandan policeman was found murdered in North Darfur.

The World Food Programme, the largest UN humanitarian agency, has cut rations by half because banditry has made the roads increasingly dangerous.

Since UNAMID took over from a small African Union force on December 31, only 7,600 troops and 1,500 police are on the ground -- barely a third of the projected total of 19,500 soldiers and 6,500 policemen.

The force lacks the air transport and cover desperately needed to support troops across terrain with limited roads, as well as transport vehicles.

Aid officials accuse the SLA Minnawi faction of contributing to growing insecurity in north, as well as south Darfur.

Recent reports have also suggested that Minnawi, who was the key signatory of the 2006 agreement, is mulling the possibility of leaving the government and returning to the armed struggle.

The United Nations says up to 300,000 people have died from the combined effects of war, famine and disease and more than 2.2 million fled their homes since the conflict broke out in February 2003.

Sudan says 10,000 have been killed.

The conflict broke out when ethnic minority rebels took up arms against Khartoum and state-backed Arab militias often called Janjaweed, fighting for resources and power in one of the most remote and deprived places on earth.

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