Sudan's government says it has agreed to a ceasefire with two rebel groups in the country's western Darfur region.

A government official says the parties reached the agreement at peace talks taking place this week in neighboring Chad. He said the ceasefire will allow the delivery of humanitarian aid to the Darfur region.

Delegations from the government and rebels began direct face-to-face discussions Tuesday in the Chadian capital, N'Djamena. The parties came together with Chad's President, Idriss Deby, and observers from the European Union and the United States.

Representatives of the two main rebel movements in the Darfur region insisted on the observers' involvement before they would meet with the Khartoum government. But, until Tuesday, the government had resisted the outside presence.

The United States has been pressing Sudan's government and Darfur rebels to reach a peace deal. President Bush said he has voiced his concerns over the fighting directly to Sudan's President Omar Hassan al-Bashir.

The rebel groups -- the Sudan Liberation Movement and the Justice and Equality Movement -- launched their revolt against Khartoum in February 2003, accusing Sudan's Arab-controlled government of subjugating its ethnic-African population. The resulting conflict has left over 650,000 people homeless, with tens of thousands fleeing into neighboring Chad.

Some information for this report provided by AP and Reuters.