Sudanese forces bombed the outskirts of a rebel-held town in southern Darfur Monday as the U.N. secretary general said peacekeepers would not heed a government request to leave the area.

Some 5,000 residents were taking refuge around the peacekeepers' compound, the spokesman for the peacekeepers, Nourredine Mezni, confirmed to the Associated Press.

Sudan told the peacekeepers on Sunday to leave so government forces could retake the town after rebels seized it. It was Sudan's first such request, U.N. officials said — and a challenge to the fragile international mission.

But U.N. Secretary-General Ban Ki-moon said the joint U.N.-African Union peacekeeping force will remain in the town of Muhajeria. He said all sides needed to show restraint and urged the rebels to pull out of town.

"I urge maximum restraint on President Omar al-Bashir and have urged the Justice and Equality Movement rebels to withdraw from the city to protect innocent civilians," Ban told journalists in the Ethiopian capital, Addis Ababa.

But JEM spokesman Ahmed Tugod said his forces, which captured the town Jan. 15, would stay and fight.

Both Tugod and Mezni confirmed that government planes were bombing the outskirts of the town, which has about 30,000 people.

The peacekeeping force is there to protect civilians displaced by the six-year civil war in Sudan's arid western region.

Sudanese forces frequently bomb rebel areas in Darfur, despite a U.N. Security Council ban on military flights over the region.

U.N. and AU officials say they want the peacekeeping force to reach its full capacity of 26,000 soldiers and policemen by June.

But Sudan regularly challenges the U.N.'s presence in the country. In January 2008, Sudan's army attacked a convoy of U.N. peacekeepers in Darfur, critically injuring a driver.

Rebels took up arms in Darfur region in 2003, citing neglect and marginalization by the central government. So far, 300,000 people have died and 2.7 million have been displaced.