The Yemeni army launched an offensive against fighters in Abyan province five days ago, targeting a group that had attacked a military camp outside the town of Lawdar.
On Friday, the military intensified those operations, sending an elite anti-terrorism unit from the capital Sanaa to join the offensive, local officials said.
The defence ministry said that at least 28 fighters had been killed in clashes west of Lawdar on Friday, according to a statement on its website.
It said that hours of fierce battles drove al-Qaeda fighters out of the town of Zara, and that two senior al-Qaeda members had been arrested.
Local officials told the Reuters news agency that three fighters and three tribesmen who had been fighting alongside government forces had been killed in separate clashes outside Lawdar.
Hundreds dead
The clashes have brought the death toll since fighting began on Monday to nearly 200 people, according to the ministry's figures.
A local official told Reuters that Yemeni air force jets bombed two sites held by Ansar al-Sharia, a group affiliated with al-Qaeda. No casualties were reported in that attack.
The group said in an emailed statement on Friday that its fighters had killed 37 tribesmen who had been fighting for the government in the last two days. It said seven of those men had been killed on Friday.
The statement said that the group's fighters launched a rocket at the house of a security chief in the southern city of Aden, killing three security officers during the ensuing clashes.
Ansar al-Sharia seized control of a significant area of territory in Abyan during the year-long uprising that led to the overthrow of former President Ali Abdullah Saleh.
