African Union peacekeepers in western Sudan's Darfur region have complained that 20 heavily armed soldiers from a rebel group intimidated staff members at AU headquarters.

In a statement issued Friday, officials said rebels from the Sudan Liberation Movement showed up at AU headquarters in the regional capital, El Fasher, earlier this week. The statement said the rebels threatened AU staff and interfered with the work of the peacekeepers, but it was not specific as to what happened.

Under a peace agreement signed in 2006, the AU has been paying salaries to some rebel groups working with the peacekeepers. But it recently cut the payments because it ran out of money.

The intimidation is just the latest in a series of threatening incidents by the SLM rebels.

An estimated 200,000 people have died and more than two million others have fled their homes since violence between rebels and the government started in 2003.