SANAA: At least eight Yemeni soldiers and five militants were killed when gunmen attacked an army checkpoint in the central Maarib province on Tuesday, a local official said.
In the southern city of Lawdar, where 57 people were killed on Monday in clashes between government forces and fighters from al Qaeda-linked group Ansar al-Sharia, fighting was intensifying, residents said.
Two tribesmen fighting alongside government forces were killed, they said.
New President Abd-Rabbu Mansour Hadi, who took over in February after mass protests against his predecessor Ali Abdullah Saleh, is under pressure from Washington to fight his country's al Qaeda branch.
On Tuesday, gunmen in vehicles fired on the army checkpoint in Abar, some 300 km east of the capital Sanaa, killing eight soldiers and wounding four before fleeing, a local official said.
Five of the militants were also killed.
The official, who spoke on condition of anonymity, blamed al Qaeda-linked militants for the attack, but it was not clear if they were part of Ansar al-Sharia.
The group claimed on Monday it had captured a large cache of arms and ammunition, including four tanks and anti-aircraft guns during fighting with Yemeni troops in Lawdar.
Residents said fighting intensified on Tuesday with warplanes bombing two sites held by the fighters 10 km west of Lawdar, destroying at least one of the tanks the group had seized a day earlier.
According to a Defence Ministry website, some of the militants killed on Monday were foreigners, including some from Saudi Arabia.
The militant group seized control of a significant amount of territory in the southern province of Abyan during the turmoil that led to the replacement of Saleh by his deputy.
Saudi Arabia and the United States backed the power transfer in hopes it would help prevent a slide into chaos that could provide al Qaeda a foothold near key oil shipping routes.
Conflict with militants in the south is only one of several challenges facing Hadi, who took office vowing to fight al Qaeda only to have more than 100 soldiers killed in attacks during his first few days in power.
Yemen's main airport in Sanaa was paralysed for a day after officers and tribesmen loyal to Saleh forced it to close in protest at the sacking of the air force commander, a half-brother of Saleh.
A government official said they backed down only after pressure from the United States and Gulf countries, which had crafted the deal that made Hadi president.
Washington, which has pursued a campaign of assassination by drones and missiles against alleged al Qaeda targets in Yemen, is also pressing Hadi to unify the military, which split between Saleh's foes and allies last year.