Local officials and residents said the fighting occurred on Jebel Yasuf, a mountain 10 km from the southern town of Lawdar, where dozens of people have been killed since Monday after Ansar Al-Shariah militants attacked an army camp. At least eight people were killed in continued fighting in the vicinity on Tuesday.

Militants, emboldened by a year of upheaval in Yemen, want to exploit weakened government control to spread their influence. In Abyan, where Lawdar is located, they already hold large swathes of territory.

A senior government official said the fighting around Lawdar marked a turning point in the army’s confrontation with Ansar Al-Shariah following a series of defeats by the militant group.

“The battle of Lawdar is considered a decisive one for the army against the terrorist groups and a prelude to the cleansing of all towns seized by militants in the province of Abyan,” said the official. He said 10 militants had also been captured.

The Defense Ministry said in a text message it had destroyed a number of checkpoints set up by militants on a main road linking Lawdar to the neighboring province of Al-Bayda, re-opening the route. It also cited unnamed military sources as saying that Pakistani and Somali nationals were among the militants killed in the Lawdar area.

President Abd-Rabbu Mansour Hadi vowed to fight Al-Qaeda and its affiliates when he took office earlier this year after his predecessor quit under pressure from anti-government protesters and foreign powers anxious to halt a slide into mayhem.

Militants have since stepped up their operations against the army, carrying out a string of deadly attacks. In return, the Yemeni Air Force has launched air strikes on suspected militant strongholds and the United States has joined in with drones.

The United States fear Yemen is becoming a major front in its campaign against the militant network, which has been dealt a number of blows over the past year, not least the killing of its founder and leader Osama Bin Laden.