The defence ministry initially said the fighting erupted when Al-Qaeda militants attacked an army checkpoint, but the official SABA news agency later said it was a dispute between soldiers and a group of tribesmen, six of whom were killed.
Officials contacted by AFP also denied the defence ministry's report, saying the fighting broke out after a group of bodyguards escorting a tribal chief refused to hand over their weapons.
Clashes between security forces and tribesmen are more rare in southern Yemen than battles pitting troops against Al-Qaeda in the Arabian Peninsula (AQAP), the local affiliate of the global terror network founded by Osama bin Laden.