Aden: Clashes on Friday in south Yemen between security forces and armed groups, including Al-Qaeda militants, as well as separatists killed 29 people, a security official said.
Fierce gunfights erupted when armed men attacked police centres in Lahj, north of Aden, the official said.
He said 29 people, including 27 members of the security forces, were killed.
Al-Qaeda-linked Ansar al-Sharia militants took part in the fighting alongside other armed "outlaws", said the official, in an apparent reference to southern separatists.
Earlier, another security source said five people, including two police, were killed in the clashes, adding that the southern separatists attacked security forces.
Al-Qaeda is active in southern Yemen where separatists demand secession of the regions of the formerly independent South Yemen from the north.
President Abedrabbo Mansour Hadi has taken Aden as a base after fleeing last month a house arrest in Sanaa under Shiite Huthi militia.