U.N. peacekeepers say two Sudanese aid workers have been killed in an ambush in Darfur. 

A peacekeeper spokesman, Kemal Saiki, says gunmen on horses and camels shot the humanitarian workers with Aide Medicale Internationale. 

He says the gunmen opened fire on the workers' vehicle as they drove by a truck the gunmen were robbing.

Four people were also wounded in the attack on the road between Khor Abeche and Darfur.

Tensions have mounted in Darfur ahead of an expected decision by judges from the International Criminal Court on whether to issue an arrest warrant for Sudan's president on charges he orchestrated war crimes in the region.

U.N. Secretary-General Ban Ki-moon says Sudan must cooperate with the court and should ensure the safety of U.N. peacekeepers and Sudanese civilians.

The United Nations says an estimated 300,000 people have been killed and another 2.7 million have been forced from their homes since fighting erupted in 2003.

Sudan says only 10,000 people have died as a result of the conflict. 

Some information for this report was provided by AFP and Reuters.