African Union Troops Stretched Thin in Darfur

A group of Darfurians fled for their lives across the desert, having survived at attack by the dreaded Sudanese militia known as the Janjaweed. In the distance, their village was still burning.

People are dying there. One man pleaded to a soldier standing by, but all the African Union peacekeepers could do was take notes. Their mandate does not allow them to intervene.

"The African Union has 5,500 troops and 1,500 police officers," said Cameron Hume, U.S. charge d'affaires for Sudan. "It's too big an area, and they can't provide security for civilians."

If the A.U. troops fanned out, each one of them would patrol an area the size of Manhattan.

In the last three months, 250,000 new refugees have swelled the ranks of the 2.5 million already displaced.

Relief supplies are running out. At the first of this month, food rations were cut in half. The camps are now a tinderbox of fear and resentment.

An African Union police station in North Darfur was burned down two nights ago by an angry mob -- but it wasn't done by the Janjaweed or by any armed militias. The damage was done by frustrated refugees. Among the displaced and disposed, tension is simmering.

"Well, they look friendly for now, but it only needs one person to shout something and it just explodes," said African Union Maj. Jomo Tayana.

The U.N. Security Council has now taken the first steps toward replacing the A.U. with a larger force of U.N. peacekeepers.

"It will take months to get the U.N. force on the ground, and Sudan needs to be convinced," said Jan Egland, the U.N. relief coordinator.

Sudanese officials told ABC News they don't even favor bolstering the African Union.

"I don't think there is a need to expand the mandate," said Magzoub Al-Khalifa, an advisor to Sudanese President Omar el-Bashir.

Part of the problem is that the Sudanese government forces are one of the main groups the A.U. is supposed to monitor.

Recently, the government imposed a nighttime curfew in Darfur. The A.U. is so weak it complies. As the sun sets, A.U. forces retreat to their bases, leaving the refugees all but defenseless.

ABC News's David Wright reported this story for "World News Tonight."