Al Qaeda in Yemen has killed at least 20 government soldiers. Twenty five more were captured when two army posts were attacked before dawn on Monday outside Zinjibar, the provincial capital of Abyan province.
A leading Al Qaeda figure in Yemen was killed by a US drone on Sunday.
Fahd al-Quso was wanted in connection with the bombing of the USS Cole in Aden in October 2000.
A boat packed with explosives blew a hole in the destroyer's side, killing 17 sailors and wounding 40.
The United States had offered a reward of $US5 million reward for information leading to Quso's capture or death.
The drone strike was reportedly carried out by the CIA with the authorisation of the Yemeni government.
Zinjibar has been controlled by groups linked to al-Qaeda in the Arabian Peninsula since May 2011.