African Union officials say rebels in Sudan's troubled Darfur region have released most of the 18 kidnapped AU workers following negotiations.

The workers were taken Sunday in the town of Tine on the Chad-Sudan border.  Officials say the 18 included military observers and civilian police, and an official from a Darfur rebel group, the Justice and Equality Movement.  African Union spokesman Noureddine Mezni says it is unclear how many of the hostages were released.

AU officials say the kidnappers are believed to be from a dissident faction of the Justice and Equality Movement.

More than six-thousand African Union peacekeepers are in Darfur to monitor a cease-fire between pro-government forces and non-Arab rebels.

Two AU peacekeepers from Nigeria and two civilian contractors were killed Saturday in an ambush the AU blamed on the main Darfur rebel group, the Sudan Liberation Army.  A third peacekeeper died Sunday from wounds.

Some information for this report provided by Reuters. AFP