CAIRO, Egypt - The United Nations evacuated 71 aid workers from the largest refugee camp in Darfur Tuesday after gunmen looted their compounds, leaving some 130,000 refugees virtually without humanitarian help.

United Nations Secretary General Kofi Annan(C) bids farewell to members of the media after his last scheduled press conference. Annan used his last press conference to defend his 10-year stewardship of the United Nations and to make one last push to end the tragedy in Sudan's Darfur region. [AFP]

It was the largest single instance of an aid worker evacuation since the UN launched its large-scale humanitarian campaign in Darfur in 2004. Over the past year, worsening violence in the war-ravaged region in western Sudan has made delivering vital aid to hundreds of thousands of residents difficult to impossible.

More than 20 gunmen raided several humanitarian compounds in the South Darfur refugee camp of Gereida late Monday, harassing staff and stealing vehicles, communication equipment and money, the UN Office for Coordination of Humanitarian Affairs said in a statement.

Though no aid workers were hurt in the attacks, the situation was considered too unsafe and the UN said it airlifted the 71 out on Tuesday.

The UN said it was the eighth evacuation of endangered aid workers it has had to carry out so far this month in Darfur.

"More than 400 (workers) have been evacuated this month, the situation is getting worse and worse," OCHA spokeswoman Dawn Blalock said by telephone from Sudan.

A handful of aid workers chose to remain in Gereida, but the "the vast majority" left the camp, Darfur's largest with some 130,000 refugees, she said.

The attacks were "preventing humanitarian organizations from providing life-saving assistance" to refugees, UN humanitarian coordinator Manuel Aranda da Silva said in the statement.

Some 15,000 aid workers operate in Darfur, including 1,000 non-Sudanese.

The UN provides food and other supplies to 2.5 million refugees and to another 1 million vulnerable civilians in the region. Nearly four years of fighting between ethnic African rebels and the Arab-dominated central government have killed more than 200,000 people in Darfur.

Violence has only worsened since the government signed a peace agreement with one rebel group in May. Other rebel factions refused to join the deal, and Khartoum opposes a plan to replace the overwhelmed African Union force in the region with some 20,000 United Nations peacekeepers.

The UN Security Council gave its unanimous backing Tuesday to a hybrid UN-African Union force for Darfur and urged all parties to quickly beef up the beleaguered African force on the ground. After a meeting in Addis Ababa, Ethiopia, on Nov. 16, Secretary-General Kofi Annan announced an agreement in principle with Sudanese officials to form a hybrid mission.

The UN said it could not identify the gunmen behind the attack in Gereida, but pointed out that the camp was under the control of followers of Minni Minawi, the rebel leader who signed the Darfur peace agreement with Khartoum.

With radio equipment and twelve vehicles stolen, Blalock said the incident was the single biggest attack on aid workers in Darfur.

Several high-ranking commanders from Minawi's rebel group have recently defected to rejoin the rebellion, saying that their leader has become powerless to protect civilians since he agreed to a cease-fire and was named presidential adviser.

A UN official in Darfur said Minawi defectors seeking new equipment to resume their fight against the government were suspected in the looting of the UN gear. He spoke on condition of anonymity because he was not authorized to talk to the media.

Spiraling Darfur violence has increasingly spread to neighboring countries, and Chad said more than 30 civilians were slain in recent raids by the Sudanese pro-government janjaweed militia.

The attackers burned homes in two villages near Chad's volatile eastern border with Sudan, mutilating victims, Chad's Communications Minister Hourmadji Moussa Doumgor said in a statement late Monday. Among those killed were 15 civilians, including five Sudanese refugees, an imam, a woman who was set alight and a man who was disemboweled, Doumgor said. Eight government soldiers were also killed.

Four janjaweed were taken prisoner and nine were killed during the attack on the villages of Aradib and Habile, Doumgor added.

Khartoum denies backing the janjaweed - who are blamed for the worst atrocities in the Darfur conflict - and says western aid groups and media vastly exaggerate the humanitarian crisis.

The UN Secretary General's former representative in Sudan said Tuesday that the government had massively armed the janjaweed and supported their killing of civilians.

Jan Pronk, who was expelled from Sudan in October for saying government troops had twice been beaten by rebels, said the UN Security Council had done little to defend him when he was expelled.

As a result, "the UN (staff) are being marginalized and harassed by the government" in Sudan, Pronk told the Al-Jazeera English TV channel.