A Darfur rebel group says Sudanese government troops have arrested six of its fighters who are serving with a regional cease-fire commission.

The rebel Justice and Equality Movement says the fighters were arrested overnight at an African Union peacekeeping base in Darfur's main town of El-Fasher.

The six JEM members were staying at the base while working with a commission set up to monitor violations of last year's Darfur peace agreement. The agreement has done little to stop violence in Darfur, where rebel groups continue to battle the government and allied militia.

The JEM called on the African Union to ensure the fighters are not harmed, and are released.

On Monday, the AU mission in Sudan formally transfers its authority to the new, joint mission run by the AU and the United Nations.

The new peacekeeping force is projected to eventually have more than 20,000 troops and more than 6,000 police. A U.N.-AU statement Friday said only 9,000 uniformed personnel are in Darfur at the moment.

Deployment of the new force has been delayed because of a lack of proper military equipment, and Sudanese objections to non-African troops.

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