Khartoum, Sudan ? Helicopters rescued more than 40 aid workers who fled into the bush to escape fighting in Darfur on Monday as renewed violence flared in the crisis-plagued region of western Sudan.

African Union peacekeepers airlifted 45 people who had spent several hours hiding in the bush outside the town of Tawilla during clashes between rebels and Arab militiamen, U.N. spokesman George Somerwill said.

A tribal dispute over livestock sparked the clashes, which began Sunday and led to rebel Sudan Liberation Army forces attacking the government-allied Arab militia known as the Janjaweed, Somerwill said.

Twenty people were killed in the clashes, according to African Union monitors. Tawilla is a strategic location which the government uses to supply forces based in western Sudan, near the Chad border, and areas in Darfur’s northwest.

A Save the Children statement said a Sudanese government plane dropped several bombs on Tawilla, with one landing 50 yards from one of the organization’s feeding centers.

If the reports are correct, they represent an apparent breach of Nov. 9 accords between rebels and the government, including a Sudanese agreement to create “no-fly zones” over Darfur. Rebels and African Union mediators had demanded the zones following widespread accusations of government bombings of villages.

“Both sides have demonstrated utter disregard for the cease-fire,” Tony Porter, Save the Children’s director of emergencies, said in a statement. “Yet again innocent civilians, particularly women and children, are suffering.”