KHARTOUM (AFP) - Sudan boosted forces outside a volatile camp for displaced people in Darfur on Tuesday, sparking fears of new armed clashes, as rebels said that up to 36 people had been killed in fighting a day earlier.

Police moved into the impoverished and volatile Kalma in South Darfur on Monday. Casualty figures from subsequent clashes are impossible to verify, but residents have asked UN troops for burial sheets and protection for funerals.

Government security officers described Kalma, which one aid worker said was the size of a small city, as a den of outlaws, armed robbers and rebel movements hoarding weapons, ammunition, explosives, narcotics and stolen goods.

"It seems last night there was a build-up of security forces around the camp," one UN official told AFP.

A Kalma community leader, Adam Mohamed, told AFP by telephone on Tuesday that more security vehicles had surrounded the camp, where conditions for the 80,000 residents were miserable and homes had been washed away by rain.

"The police force will remain in its place until it enters the camp to collect the stockpiled weapons and prevent the rebels from getting inside the camp," state media quoted the South Darfur security committee as saying.

Five policemen and seven Kalma residents were wounded when gunmen inside the camp opened fire "compelling" the police to respond, the committee said.

But Ahmed Abdel Shafie, a commander in the nebulous Sudan Liberation Army that first rebelled against the government in 2003, said the death toll from Monday's shooting had risen from 27 to 36, with all the victims identified.

They included at least five women and two children, he said.

"The situation is very bad. The people are really suffering," he told AFP by telephone from Darfur in west Sudan. The people, who live in mud and straw huts, lacked medication and were having to cope with heavy rain, he said.

Mohamed, the Kalma resident, said that the death toll had climbed to 52 and that bodies were being buried at a cemetery inside the camp.

UN officials spoke about unconfirmed reports of 32 dead.

On Tuesday, internally displaced persons (IDPs) said 24 bodies were still lying in the camp and urged the United Nations to provide security for funerals and white sheets required in compliance with Muslim ritual.

The United States, which has strained relations with Khartoum, has criticised Sudan over the incursion and called for a full investigation.

The joint African Union-United Nations peacekeeping mission in Darfur said it had evacuated 49 wounded IDPs, mostly women and children, and some men to hospital in the nearby town of Nyala overnight.

International charity Medecins Sans Frontieres, which runs a clinic in Kalma, said it was trying to regain access to the camp.

"We've not had any reports of new incidents or new casualties in our clinic. At the moment we are trying to re-access the camp to get back to our normal work," Jose Hulsenbeq, MSF-Holland Darfur Coordinator, told AFP.

UN-led peacekeepers were locked in talks on Tuesday over how best to manage the crisis.

Salah Bob, a spokesman for a faction of the rebel Sudan Liberation Movement said that 22 local leaders in the camp had been arrested but could provide no further details.

Darfur peacekeepers scrapped patrols to Kalma on Monday after government forces, armed with a search warrant, requested their help to hunt for weapons and wanted people in the camp. UNAMID said that violated their mandate.

UNAMID has struggled to provide security in Darfur with just over a third of the 26,000 troops they have been promised.

Darfur tensions have heightened in Sudan since the prosecutor of the International Criminal Court last month formally asked judges to issue an arrest warrant for President Omar al-Beshir.

The latest violence overshadowed the arrival in Sudan of Djibril Bassole, the new international mediator trying to find a political solution to end five years of war in Darfur.

The United Nations says that up to 300,000 people have died and more than 2.2 million fled their homes since the conflict erupted in February 2003. Sudan says 10,000 have been killed.

The war began when ethnic minority rebels took up arms against the Arab-dominated Khartoum regime and state-backed Arab militias, fighting for resources and power in Africa's biggest country.