Pakistani jets bombed suspected Taliban hideouts after a stray mortar shell crashed into a mosque during prayers, part of a wave of violence that claimed nearly 70 lives in 24 hours along the northwest region bordering Afghanistan, officials said Monday.

The clashes came as U.S. Gen. David Petraeus, who oversees American war efforts in Afghanistan and Iraq, praised Pakistan's ongoing offensive against insurgents. Many of those al-Qaeda and Taliban fighters are suspected in attacks on U.S. troops in Afghanistan.

The air strikes hit a guesthouse used by militants in the village of Kani Guram in South Waziristan tribal region close to the Afghan border, where government forces have been preparing for a high-stakes offensive against Pakistani Taliban chief Baitullah Mehsud.

Four militants died, said three intelligence officials who spoke on condition of anonymity because they were not authorized to release the information. It was not possible to independently verify the reports because journalists have little access to the dangerous region.

Late Sunday, a stray mortar shell hit a mosque during prayers in Azam Warsak in South Waziristan, killing three tribesmen and wounding seven, intelligence officials and a witness said.

"The mosque was destroyed, and we could hardly bring out the dead and injured," said a man who gave his name as Wazir. He escaped the strike unharmed.

It was not clear who fired the mortar.

The Taliban's Mehsud has been blamed for a string of deadly suicide bombings across the country in recent weeks. Mehsud also was accused in the 2007 assassination of former prime minister Benazir Bhutto, though he has denied responsibility.

An ambush Sunday claimed by the Taliban killed 16 soldiers in North Waziristan, another militant stronghold. That prompted the army's top spokesman to warn it would punish tribes that harbour militants in that region if the violence continued.

Maj. Gen. Athar Abbas said 10 suspected militants were also killed in the attack.

The military also is pursuing an offensive to oust Taliban militants from the northwest's Swat Valley. That operation, which also affected surrounding districts, has displaced more than two million people.

The military says about 1,600 militants have been killed in the two-month-old offensive, including eight more since Sunday.

Also Monday, Pakistani security forces launched an early morning raid on a suspected militant hideout in Tank, a small city near South Waziristan, killing two suspected militants and arresting nine others, senior police officer Abdul Rasheed said.

Separately, 21 militants died in overnight clashes with an anti-Taliban militia in Kurram tribal region, a tribal elder and lawmaker said. Ali Akbar Toori and lawmaker Sajid Toori said four militiamen were killed and 35 were injured in the attack, which appeared to be an attempt by insurgents to take over the area.