(Updates number of troops killed, wounded)
SANAA, Jan 28 (Reuters) - A suicide bomber killed 11 Yemeni soldiers on Monday after troops backed by tanks attacked an al Qaeda stronghold following the collapse of talks to free three Western hostages, local officials and residents said.
Tackling lawlessness in the impoverished Arabian Peninsula state, which flanks the world's biggest oil exporter Saudi Arabia, is an international priority. The United States views Yemen as a frontline in its struggle against al Qaeda.
A Finnish couple and an Austrian man, who were studying Arabic in Yemen, were snatched last month by tribesmen in the capital Sanaa. They were later sold to al Qaeda members, and transferred to the southern al-Bayda province, a Yemeni official told Reuters earlier this month.
A government official said the army began its offensive in al Qaeda's al-Manaseh stronghold in al-Bayda early on Monday after the militants rejected demands to release the hostages.
Residents said they saw dozens of tanks and armoured vehicles moving at dawn towards al-Manaseh. "A few hours later, army forces started shelling. We could hear explosions," a man who gave his name only as Abdullah told Reuters by telephone.
In an apparent reprisal for the offensive, the suicide bomber drove a car laden with explosives into an army checkpoint in Radda, a town near al-Manaseh. Eleven soldiers were killed and 17 wounded, the defence ministry said. An earlier report from local officials put the death toll at eight.
Militants also ambushed and killed three other soldiers near Radda in a separate attack, according to medics.
No figures were immediately available on militant casualties.
U.N. ENVOYS FLY IN
The kidnapping of Westerners occurs sporadically in Yemen, mostly by tribesmen seeking bargaining clout in disputes with the authorities or by al Qaeda militants.
Washington and other Western governments regard Yemen-based al Qaeda in the Arabian Peninsula (AQAP), which has planned attacks on international targets including airliners, as one of the most dangerous offshoots of the global militant network founded by Osama bin Laden.
There have been dozens of killings of security and military officials by suspected al Qaeda gunmen in the past year, suggesting AQAP remains resilient despite increased U.S. drone strikes and an onslaught by government forces.
U.N. Security Council envoys flew to Yemen amid tight security on Sunday to show support for a U.S.-backed power transfer deal in danger of faltering and plunging the country further into chaos.
Yemen has struggled to restore normality since President Abd-Rabbu Mansour Hadi was elected in February 2012 following a year of protests that forced his predecessor Ali Abdullah Saleh to step down after 33 years in power.
AQAP and other militant groups took advantage of the chaos in the run-up to and aftermath of Saleh stepping down, seizing entire towns and areas in the south.
Under the power transfer deal, Hadi is overseeing reforms for a two-year interim period to ensure a transition to democracy. Presidential and parliamentary elections are expected in 2014. (Reporting by Mohammed Ghobari; Writing by Mahmoud Habboush and Rania El Gamal; Editing by Sami Aboudi and Pravin Char)