At least 23 people have been killed after suspected al-Qaeda-linked fighters attacked a military camp in southern Yemen, residents and local officials have said.
Fighting near the city of Lawdar erupted on Monday when fighters from Ansar al-Sharia launched a dawn assault on the camp, which is in Abyan province, about 120km from the southern port city of Aden.
The fighters seized control of a significant amount of territory in Abyan during the turmoil that led to the replacement of former president Ali Abdullah Saleh by his deputy, Abd-Rabbu Mansour Hadi.
Saleh had been in power since 1978 and unsuccessfully battled street protests that culminated into his stepping down under a deal sponsored by the six-nation Gulf Co-operation Council (GCC).
Quoting officials and residents, the Reuters news agency reported 18 fighters were killed in the clash with the army and five when warplanes bombed a checkpoint they were holding.
Nine soldiers and one tribesman fighting alongside them were also killed.
A military official said the army drove the fighters away from the area around the camp. The fighters said in an emailed statement that none of their men was killed in the clash, and threatened to attack Lawdar.
Mohammed Nasser, a resident of Lawdar, speaking by telephone with the sound of artillery and small arms fire audible, said the fighting lasted three hours.
"It is not the first attempt [by the group] to take control, but it's the biggest attack yet," he said.
A local official said tribal militiamen joined the fighting alongside the military, and that at least 10 soldiers and tribesmen were wounded.
The conflict with Islamists in the south is posing a major challenge for Yemen's new president.
Hadi took office vowing to fight al-Qaeda, only to have more than 100 soldiers killed in a series of attacks in his
first days in power.
The US, which is working with Saudi Arabia to prevent al-Qaeda from getting a foothold near key oil shipping routes, has pursued a campaign of assassination by drone and missile against alleged al-Qaeda targets in Yemen.
Washing wants Hadi to reunify an army that is split between Saleh's foes and allies last year, and focus it on "counter-terrorism".
The latest developments come days after Yemen's main airport in the capital, Sanaa, was paralysed for a day after Hadi sacked the air force commander, a relative of Saleh, last Friday.
Pro-Saleh officers responded by blockading the airport with vehicles.
A government official said they backed down only after warnings from the US and the GCC.