KHARTOUM, Sudan (AP) -- The United Nations has said dozens of men on horseback armed with machine guns and rocket-propelled grenades have ambushed Nigerian peacekeepers serving with the joint U.N.-African Union force in Darfur.

The U.N.-AU mission known as UNAMID said in a statement Thursday that no casualties were reported.

About 50 to 60 armed men on horseback and dressed in military camouflage ambushed the peacekeepers Wednesday afternoon along the new airport road near El Geneina in West Darfur state.

They stole rifles, ammunition, telephones and cash.

UNAMID did not say who was suspected in the attack.