Young SLA fighters at Marla, Darfur.

NAIROBI, 22 Jun 2005 (IRIN) - Violence flared up in the western Sudanese state of South Darfur on Sunday when rebel fighters of the Sudan Liberation Army (SLA) attacked and killed a number of Sudanese soldiers, a UN spokesperson said.

The attack on government troops took place in the area of Manawashi, about 78 km north of Nyala, the capital of South Darfur State.

"We know for a fact that an attack by SLA rebels took place, but we don’t know why they attacked or how many casualties there are," Radhia Achouri, spokeswoman for the UN Mission in Sudan (UNMIS) said on Wednesday.

A humanitarian source reported that four Sudanese soldiers were killed and three others wounded during the attack, adding that it was possible the SLA leadership had been unable to control its forces on the ground.

He said the SLM could have carried out the operation to achieve political leverage in the Abuja negotiations by showing it could strike anywhere at any time.

"As of yesterday [Tuesday] afternoon, the Sudanese military has sealed off the area and has restricted the movement of displaced persons [IDPs] as well as NGOs," the source added. "The IDPs are currently cut off from assistance."

"I have no details at the moment; our people are investigating the incident," an AU military information officer in Darfur, who only identified himself as Maj Willy, said.

"The situation is calm but tense," Achouri added. "The population fears that the SLA will come back or that the government will retaliate."

Asked what UNMIS was doing to defuse the tensions in the area, the spokesperson said the AU was handling the incident.

"They have all the mechanisms and the mandate to deal with this issue," she said.

The attack comes at a time when the AU, which is mediating in the Darfur peace talks in the Nigerian capital of Abuja, is attempting to bring back the warring parties to the negotiating table.

Meanwhile, the UN Under-Secretary-General for Humanitarian Affairs, Jan Egeland, told the UN Security Council during a briefing on Tuesday that while the number of large-scale attacks on civilians in Sudan had decreased, grave protection concerns persisted.

"Imagine the quality of life for those that are caught in these cycles of violence living in constant terror. This has an enduring impact on individuals and tears the very fabric of society. Such endemic violence cannot continue," Egeland said.

He called for a strategic deployment of troops around camps to provide area security for the displaced, in areas of unrest to prevent new displacement, and in areas of origin to facilitate voluntary and safe return.

The AU mission in Darfur provided a prime example of the positive impact even a relatively small security presence could bring, he added.

In a statement read out by its President, Michel Duclos of France, the Council expressed deep concern at the use of sexual violence as a weapon of war, and called on all states to put an end to impunity in that regard.

The war in Darfur pits Sudanese government troops and militias - allegedly allied to the government - against rebels fighting to end what they have called marginalisation and discrimination of the region's inhabitants by the state.

More than 2.4 million people continue to be affected by the conflict, 1.86 million of whom are internally displaced or have been forced to flee to neighbouring Chad.