A US missile strike and clashes between extremist gunmen and tribesmen killed at least 20 militants on Tuesday in northwest Pakistan near the Afghan border, officials said.
The drone attack destroyed a mountain hideout in the district of North Waziristan, killing 10 militants including Al-Qaeda-linked suspects.
North Waziristan is known as a stronghold of Taliban and Al-Qaeda-linked fighters and increasingly targeted by the covert US drone war since a suicide attack killed seven CIA employees in Afghanistan.
The missiles hit a compound used by militants near Datta Khel village, 20 kilometres (12 miles) west of Miranshah, the main town of North Waziristan, Pakistani security officials said.
The exact identity of the militants was unclear and it was not immediately known whether there were any high-value targets.
"At least 10 militants, mostly foreigners, were killed," one Pakistani security official told AFP on condition of anonymity, adopting a term used widely in Pakistan to refer to Al-Qaeda-linked suspects.
"Five missiles were fired by US drones," he added.
Three other security officials confirmed the missile strike and gave the same death toll, while a local intelligence official described the target as a mountain hideout for militants. Arabs were said to be among the dead.
Militants cordoned off the area and were searching the rubble, where two cars were also destroyed in the strike, a local administration official said.
US drone attacks routinely target Taliban and Al-Qaeda commanders in Pakistan's semi-autonomous tribal belt, which Washington calls the global headquarters of Al-Qaeda and the most dangerous region on Earth.
They have increasingly homed in on North Waziristan, which borders Khost province, where a Jordanian doctor turned Al-Qaeda double agent blew himself up on December 30 in the deadliest attack on the US spy agency in 26 years.
The drone war has killed a number of high-profile targets, including Pakistani Taliban chief Baitullah Mehsud and possibly his successor Hakimullah Mehsud, but the raids fuel anti-American sentiment in Muslim Pakistan.
US officials say the strikes are a vital weapon in the war to defeat Al-Qaeda and reverse the Taliban insurgency in Afghanistan, where Washington is leading a major troop surge this year in a bid to end the eight-year war.
More than 830 people have been killed in more than 90 US strikes in Pakistan since August 2008, with a surge in the past year as President Barack Obama puts Pakistan at the heart of his fight against Al-Qaeda.
Elsewhere in the tribal belt, a gunfight between militants and local tribesmen killed at least 10 rebels and wounded another seven in the Kurram district, local officials said.
"A group of 50 militants wanted to kidnap a member of the local anti-Taliban tribal force but tribesmen foiled the attempt," local official Haider Khan said.
Local intelligence officials in the area also confirmed the incident and said the Taliban later escaped, leaving behind dead bodies and wounded militants, who were handed over to security forces.
Washington is pressuring Islamabad to do more to dismantle militant border sanctuaries, as it struggles against the Taliban in Afghanistan, where more than 121,000 US and NATO troops are based.
Taliban and Al-Qaeda-linked groups are blamed for a wave of suicide and bomb attacks that have killed more than 3,000 people across Pakistan since 2007.
Pakistan's military claims to have made big gains against Taliban and Al-Qaeda strongholds over the past year, following major offensives in the northwestern district of Swat and South Waziristan.
But last Friday, a twin suicide attack killed 57 people in the deadliest assault on Lahore and just days after a car bombing killed 15 in the same city.