Dozens of Rwandan soldiers flew into Sudan's troubled Darfur region Sunday, the first foreign armed forces deployed in the area since Arab militiamen began a rampage against black African farmers, killing tens of thousands.

The 141 Rwandan troops, as part of an African Union force, were airlifted to the huge, desert province of western Sudan on a mandate to protect unarmed military observers monitoring a four-month cease-fire that humanitarian groups say has largely been ignored by the Arab militiamen, called the Janjaweed.

Rwandan President Paul Kagame has said his troops would also use force to protect endangered civilians.

As many as 50,000 people have been killed in the fighting, 1.5 million have been forced from their homes and 2.2 million are in urgent need of aid, according to the U.N. and U.S. officials, who have called Darfur the worst humanitarian crisis in the world.

The U.N. Security Council passed a resolution on July 30 that gave Sudan 30 days to act to disarm the militiamen. The government has been accused of backing the Arab militiamen in its effort to put down rebel groups.

The Rwandan troops are part of a 300-member African force Sudan was pressed to allow into Darfur.

The troops were trucked to a camp immediately after landing in El Fasher, capital of the Northern Darfur state. They will be deployed to five other areas, including a region in neighboring Chad where thousands of people have sought refuge.

Nigerian troops are expected to enter Darfur on Aug. 25, the African Union said in a statement.

"All my troops are on board; we hope our mission in Darfur will be of great benefit to our African brothers there," Maj. Emmanuel Rugazora, commander of the Rwandan army contingent sent to Darfur, said while boarding a transport plane.

An advance team of a dozen Rwandan troops was airlifted to Darfur on Saturday aboard a cargo aircraft carrying armored personnel carriers, arms, ammunition and other military supplies for the troops. Rwanda has been pushing African leaders to give the troops a formal mandate to use force to stop attacks on civilians.

An officer checks a soldier's equipment as Rwandan troops, part of an African Union force, prepare to leave Kigali, Rwanda's capital, for Sudan's Darfur region.