Suspected Al-Qaeda jihadists have executed three Yemeni soldiers they captured in an ambush of an army convoy backing an offensive against extremist strongholds in the south, a security official said Wednesday.
"Residents found the bodies of three soldiers, bearing marks of torture, near a road intersection in Ataq," the official said, referring to the capital of Shabwa province in south Yemen.
Yemen's security forces on Tuesday launched an offensive against militant bastions in Shabwa and neighbouring Abyan provinces, with 36 people -- 21 soldiers and 15 extremists -- killed so far, according to an AFP tally Wednesday compiled from several sources.
The three men executed were among 15 soldiers captured by militants during Tuesday's ambush near Al-Saeed, one of several towns in Shabwa province targeted in the offensive by Yemeni troops, who are backed by tribal militia, the official said.
The militants were armed with machineguns and rocket-propelled grenades when they seized a troop carrier with the soldiers inside and destroyed three other vehicles, army sources said.
abductors released two soldiers hours later, after "severely beating" them, the security official said, adding that the fate of the other 10 troops remains unknown.
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After the three bodies were discovered Wednesday the army made a "tactical withdrawal" from Al-Saeed, the official said.
In Abyan province, meanwhile, three Al-Qaeda militants were killed and 10 wounded Wednesday when the army shelled the towns of Sannaj and Maajalah, an army officer said.
The launch of the ground offensive followed intense US and Yemeni air strikes on suspected Al-Qaeda targets last week that officials described as "unprecedented".
The air strikes killed 55 suspected militants in Abyan, three in Shabwa and 10 in Baida province further north, where three civilians also died, according to officials.
Military commanders are seeking to expel the jihadists from a string of small towns and hill districts in Abyan and Shabwa, where they retained a presence after a 2012 offensive in which the army recaptured major towns.
A "Friends of Yemen" meeting in London heard a call by British Foreign Secretary William Hague for donors to back Yemen's efforts to give Al-Qaeda "nowhere to hide".
Al-Qaeda in the Arabian Peninsula -- a merger of the network's Yemeni and Saudi branches -- is regarded by Washington as its most dangerous franchise and has been subjected to an intensifying drone war this year.
The jihadists took advantage of a 2011 uprising that forced president Ali Abdullah Saleh from power to seize large swathes of the south and east, from which the army has struggled to evict them, despite backing from militia recruited among the local tribes.