U.N. Secretary-General Kofi Annan warned African leaders Tuesday the humanitarian crisis in Sudan's Darfur region may lead to "a catastrophe that could destabilize the region."

The violence in Darfur (search), where thousands have been killed and more than 1 million black Africans have fled attacks by Arab militiamen, threatens to destabilize the region, Annan told 35 leaders, including Sudan's President Omar el-Bashir (search).

Annan addressed the 53-country group after visiting the western region of Darfur and meeting with people who fled to camps in neighboring Chad.

"The ruined villages, the camps overflowing with sick and hungry women and children, and the fear in the eyes of the people should be a clear warning to all of us," Annan said.

"Without action, the brutalities already inflicted on the civilian population of Darfur could be a prelude to even greater humanitarian catastrophe — a catastrophe that could destabilize the region," he said

The African Union (search) said it would send 300 troops to protect refugees in Sudan and Chad. The soldiers also will protect military observers monitoring a cease-fire in Darfur, a region the United Nations has called the world's worst humanitarian crisis.

Sam Ibok, director of the African Union's Peace and Security division, said the troops would be deployed soon, but did not give a date. He said the force would include troops from Nigeria and Rwanda. Tanzania and Botswana may also send peacekeepers.

The commitment of 300 peacekeepers marks a significant increase from the 150 unarmed African Union monitors who were expected to go to Darfur as part of an April cease-fire agreement in Sudan. A small number of African Union monitors are already there.

The United Nations has said that thousands of people have been killed and more than 1 million others were forced from their homes, most taking shelter in makeshift camps along the Chad-Sudan border.

Nomadic Arab tribes have long been in conflict with their African farming neighbors over Darfur's water and usable land. The tensions exploded into violence when two African rebel groups took up arms against the government in February 2003 over what they regard as unjust treatment by the government in their struggle with Arab countrymen.

U.N. officials and human rights groups have accused Sudan of backing the Arab militias, engaged in a campaign to violently expel African farmers from the vast western region. Annan has said the crisis is "bordering on ethnic cleansing."

The U.S. Agency for International Development (search) says many are in desperate need of help. Sen. John McCain, R-Ariz., on Monday urged quick action to prevent further death.

"This is a horrible thing that's going on," he said on CNBC. "I think that all the sanctions and all the criticism and everything is appropriate but I also think we ought to fund, we the United States of America, should fund a force made up of military from other African countries to go in there and stop this."

During a visit to the region last week, Secretary of State Colin Powell won a commitment from Sudan's President Omar el-Bashir to contain the militias and allow human rights monitors into Darfur.

Powell had earlier said that if Sudan refuses to take decisive steps to cut its ties to the Arab militias, Sudan cannot expect to have normal relations with the United States.