Elsewhere in the lawless tribal belt bordering Afghanistan, suspected U.S. missiles killed nine alleged militants, officials said.
Ten civilians and two police officers died in the suicide attack in the Bajur tribal region, while 24 people were wounded, local government official Bakhat Pacha said. The attacker, on foot, struck a market area in the region's main town, Khar, he said. The attack came a day after officials said security forces had killed 44 militants in three days of battles on the outskirts of Khar.
Pakistan waged a major military offensive against Taliban and al-Qaida insurgents in Bajur in 2008, declaring victory over the militants by February 2009. But in recent weeks, clashes and now this latest suicide attack have signaled a deteriorating security situation in the area.
The violence comes as Pakistan's army has focused on an offensive in South Waziristan tribal region, the primary stronghold of the Pakistani Taliban. That military operation is believed to have led many militants to flee to other parts of the tribal belt.
The U.S. has praised the Pakistani operations, but also wants Islamabad to pursue militants in North Waziristan, where many of the insurgent groups are focused on battling Western troops across the border in Afghanistan.
Washington has waged its own fight in Pakistan's tribal territories through its covert CIA-led missile program.
Overnight Saturday, three suspected U.S. missiles hit a compound and a bunker in the Mohammad Khel area of North Waziristan, part of a surge of the drone-fired strikes, intelligence officials said. The mountainous area is where a suspected U.S. drone is reported to have crashed on Jan. 24, they added.
Two missiles in Saturday's attack hit the compound being used by the militants, killing seven of them, the intelligence officials said. The third killed two more insurgents in the bunker, they said.
Another such missile strike early this month targeted a meeting of militant commanders in an apparently unsuccessful attempt to kill Pakistani Taliban chief Hakimullah Mehsud.