ADEN: Extremists have killed two members of an influential tribe in southeastern Yemen, tribal sources said Thursday, accusing ISIS of carrying out the executions.

"Supporters of Daesh Wednesday executed members of the Awlaki tribe after kidnapping them," a senior tribesman told AFP, using the Arabic acronym for ISIS.

Another tribal source said Hashem and Ahmed Maklam al-Tunssi were killed in Seiyun, the second largest town in Hadramawt province, where Al-Qaeda in the Arabian Peninsula (AQAP) has a significant presence.

The men belonged to the same tribe as U.S.-born radical cleric Anwar Al-Awlaki, who Washington alleges was a senior Al-Qaeda operative.

He was killed by a U.S. drone strike in Yemen in 2011.

The pro-government "Popular Resistance" force in Hadramawt confirmed the deaths of the two men in a statement accusing ISIS of the killing.

The announcement comes a day after AQAP fighters drove pro-government forces out of a town in southern Yemen that could potentially open up a supply route between their stronghold of Mukalla, in Hadramawt, and second city Aden.

At least 15 people were killed when AQAP fighters swept into Jaar, in Abyan province, before appearing to withdraw from the town.

AQAP, which has taken advantage of fighting between loyalist and rebel forces across the country, took control Thursday of a checkpoint in Jaar leading to the town of Zinjibar, where the extremists already control government buildings.

A Saudi-led coalition launched strikes on Iran-backed rebels in March after the insurgents seized the capital Sanaa and swept south towards Aden, forcing the government of President Abedrabbo Mansour Hadi to flee temporarily to Riyadh.

The United Nations says more than 5,700 people have been killed in Yemen since then, nearly half of them civilians.