A U.S. aid chief got a firsthand look at the anger among Darfur's beleaguered population Friday, when residents of a refugee camp beat up a government worker who tried to stop them from complaining to the visiting diplomat.

U.S. Agency for International Development (search) Administrator Andrew Natsios said Friday's violence sprang from "absolute rage" across the region among displaced Darfurians, who blame the Sudanese government and an Arab militia for the violence that forced them from their homes.

Natsios was touring Mornie, West Darfur's biggest camp with up to 80,000 people, hearing complaints from residents when the scuffle occurred.

An official from Sudan's Humanitarian Affairs department tried to silence those who were telling Natsious that they cannot return to their homes, as the government has recommended, because they feared more attacks by the government and the Janjaweed, the pro-government militia accused of atrocities against civilians.

Some in the crowd shouted: "Shut up, you're Janjaweed! Shut up, you're government," and began beating the official with sticks, Natsios said.

The official was conscious and bleeding from gashes across the front and back of his head before aid workers and African Union monitors were able to shove his attackers away. Last month, a mob in another camp killed an alleged Janjaweed member.

"Now it's confirmed in a terrible way that you are clearly dealing with an explosive situation," Natsios told reporters after his security whisked him from the camp, some 750 miles west of Khartoum.

Natsios, who has toured Darfur (search) this week, has pressed the Sudanese government to do more to restore calm.

The United Nations (search) estimates 50,000 Darfurians have died from disease, violence or malnutrition since February 2003, when two Darfur rebel groups began a revolt and, in response, the Janjaweed began a rampage, attacking villages and killing and raping residents.

The conflict has its roots in decades of tensions between ethnic African tribes and Arab herdsmen, who have long competed over the region's scarce resources. The rebel groups, formed from the ethnic Africans, accuse the Sudanese government of discrimination against them.

The Sudanese government is accused of backing the Janjaweed in an effort to quash the rebellion, a charge Khartoum denies.

Some of Natsios's aides said the official who was beaten or another Sudanese official had been photographing those talking to Natsios on Friday. International human rights groups have accused the Sudanese government of detaining people who complain to foreign officials, including U.N. Secretary-General Kofi Annan (search) and U.S. Secretary of State Colin Powell during their visits to the region in June, about the situation in Darfur.

"This is outrageous, they're trying to intimidate them," Natsios said.

Earlier Friday in the West Darfur capital of Geneina, Habib Makhtoum of the regional Social Affairs ministry claimed that those in the camps who complain are either rebels or had been intimidated into lying by rebels.

Thursday, Natsios had visited another camp where children showed them their drawings of armed fighters on horseback killing people and looting cattle.

"It's horrifying," he said. "I get very angry when I see this.

At the United Nations Thursday, Annan accused the Sudanese government of failing to rein in the Arab militia known as the Janjaweed. He also said that both government forces and rebels in Darfur were guilty of violating a cease-fire.

African Union-mediated talks between the rebels and the government on an overall peace deal broke down earlier this week. The Nigerian hosts and mediators are now pressing the rebels to accept a separate humanitarian accord.

Sudan's government already has agreed to sign the humanitarian accord guaranteeing access for international relief workers and promising to safeguard the return of refugees. Aid groups had earlier accused the government of blocking their work.

One rebel group, the Justice and Equity Movement, has refused to sign the humanitarian accord, saying existing accords already provide for relief, and that it is impossible to do more before the Janjaweed are disarmed.

The other rebel movement, the Sudan Liberation Army, has yet to formally present its position.

Meanwhile, the U.N. Security Council is considering a U.S. draft resolution threatening sanctions, singling out the "petroleum sector," if the Sudanese government doesn't curb the Janjaweed, start to disarm them and punish those who have committed human rights violations.