By Justin Bergman

United Nations - Arab nomads have launched violent attacks on civilians near a refugee camp in the southern Darfur region of Sudan in recent days, killing one man and injuring several others, the United Nations said on Monday.

The attacks came after the UN issued a report on Friday accusing the government-allied Janjaweed militia of killing more than 50 people in raids on villages and a refugee camp in late October. The Sudanese government has denied involvement in the raids.

Violence has escalated sharply in Darfur since the government and one rebel faction signed a peace agreement in May. Sudan has refused to allow the UN to send peacekeepers into the region to replace beleaguered African Union troops, and last month expelled the UN envoy to Sudan, Jan Pronk.

In the latest attacks, the UN mission in Sudan said several armed Arab nomads in military uniform attacked and killed a farmer on Friday about three kilometres south of the Kalma refugee camp, which is home to about 90 000 people.

A day earlier, about 18 armed Arab nomads attacked four farmers several kilometres south of the camp, the UN mission said. On Saturday, Arab nomads attacked a group of refugees who were searching for firewood about 6,5km north of the camp, the mission said.

UN spokesperson Stephane Dujarric did not offer further details in a news conference at UN headquarters in New York, but said "the displaced persons in the camps have requested more patrols by the African Union forces in Darfur."

Oliver Ulich, Sudan team leader in the UN Office for the Coordination of Humanitarian Affairs, said AU troops have recently returned to the camp after pulling out earlier, but they have since been conducting only irregular patrols. He called the area "notoriously insecure."

Elsewhere in southern Darfur, the UN mission said it had negotiated the release of four Sudanese government workers who had been captured in late October by the rebel group that had signed the peace agreement with the government.

Sudan's Arab-dominated government has long denied backing the Janjaweed, a militia of Arab nomads blamed for much of the atrocities against ethnic African villagers in Darfur since 2003, when African rebels first took up arms against Khartoum.

More than 200 000 people have since been killed, and 2,5 million displaced in the conflict.

Sudan's Foreign Ministry has said that neither the Sudanese army nor regular pro-government paramilitary groups were currently fighting rebels in Darfur, contradicting multiple reports by international observers that they were in the region. - Sapa-AP