Fierce clashes between the Yemeni army and Al-Qaeda in the country's restive south killed at least 30 soldiers and 12 militants on Sunday, medics and officials said.
"So far 30 soldiers have been killed and the toll is expected to rise as some bodies have not been transferred to hospital yet," a military official said on condition of anonymity.
He said that "many more soldiers were wounded" in the clashes south of Zinjibar, Abyan's provincial capital where the army has been battling Islamists since May.
A medic at a military hospital in the southern port city of Aden confirmed the death toll.
Military officials said Sunday's clashes erupted after Al-Qaeda linked militants tried to overrun an army post in Kud, sparking a firefight.
A local official in Jaar, a nearby extremist stronghold, said 12 Al-Qaeda militants died in the firefight. Thirty soldiers, 10 of them wounded, were captured, he added.
An official in Kud, meanwhile, told AFP that Al-Qaeda gunmen had taken away the bodies of three of the soldiers killed.
The militants also seized heavy weapons before pulling back to Zinjibar, an army source said, accusing some army leaders who had served under former president Ali Abdullah Saleh of "collaborating" with Al-Qaeda.
It was the latest in a spate of attacks against security forces since President Abdrabuh Mansur Hadi took over from Saleh and was sworn in on February 25 under a Gulf-brokered transition accord.
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On Friday, Hadi, who must restructure the army during his two-year interim period in power, named General Salem Ali Qatan to head the 31st Armoured Brigade in southern Yemen.
The post had been held for decades by General Mahdi Maqola, known for his close ties to Saleh and accused of corruption.
Zinjibar has fallen mostly under the control of Al-Qaeda militants since May at a time that protests were raging across the country against Saleh's 33-year rule.
On the day Hadi was sworn in, vowing to carry on Saleh's fight against the network, an Al-Qaeda suicide bomber blew up his vehicle outside a presidential palace in the southeastern province of Hadramawt killing 26 soldiers.
Late on Saturday, hours after a similar suicide attack killed a Republican Guard soldier in southwest Yemen, suspected Al-Qaeda gunmen shot dead a police officer Colonel Shaef al-Nahmi, also in Hadramawt, a security official told AFP.
Separately on Sunday, Abdullah Idris, the head of Saleh's General People's Congress party branch in Rada, a town southeast of Sanaa, was "seriously" wounded when his car exploded, a military official said.
His two companions were also wounded in the blast in Rada, which Al-Qaeda briefly captured in mid-January, the same source said.
Saleh had declared himself a US ally in its "war on terror" but some of his opponents accused him of exaggerating the Al-Qaeda threat in a bid to win Western support to cling to power.
Critics charge he may even have deliberately surrendered cities such as Zinjibar.