The Pakistani army says it has carried out air strikes on camps used by militants in the tribal area of South Waziristan near the Afghanistan border.
Pakistan says it has destroyed militant bases in South Waziristan
Army spokesman Maj Gen Shaukat Sultan said most of the 25-30 militants in the camps had been killed.
The army had used combat helicopters to attack the camps in the Zamzola area in South Waziristan, he said.
Much of the border region is outside government control and is believed to be a base for al-Qaeda and its leaders.
The army carried out the operation in South Waziristan early on Tuesday after receiving information that militants were hiding in five mud-walled compounds, Maj Gen Sultan said.
"We believe most of them were killed, but we don't have a body count," he said.
He said the militants included some foreigners, but "no high-value target was believed to be there".
Eyewitnesses say 10 bodies have been dug up so far. Three of them have been identified as local Mahsud tribesmen.
At least six other bodies have been identified as those of Afghan nationals, administration officials in South Waziristan say.
Other bodies are unidentifiable as they have been so badly mutilated in the attack.
Witnesses say that between eight to 10 people appear to have survived the attack with injuries, but no other details are available at the moment.
The BBC's Barbara Plett in Islamabad says this kind of strike has become rare within the last year.
Previously the army had tried to clear al-Qaeda fugitives and other foreign fighters out of the lawless border area, but it encountered such stiff resistance from local tribesmen that it signed peace deals with them.
The senior US commander in Afghanistan, Lt Gen Karl Eikenberry, said that "the enemy" was using both sides of the Afghan-Pakistani border.
"I'd also emphasise that we do have a challenge right now with command and control of the Taleban forces that has to be addressed," he told reporters in Kabul.
The general said that the number of cross-border attacks in that area last month was 200% higher than the same period a year ago. He did not give precise figures.
The Pakistani air strikes came hours after US Defence Secretary Robert Gates arrived in Kabul for talks with Afghan President Hamid Karzai.
Earlier this month Pakistan denied allegations made by the US National Intelligence Director, John Negroponte, that leaders of al-Qaeda had found a secure hideout in Pakistan from where they were re-building.
Islamabad signed controversial peace accords with militants in the semi-autonomous tribal areas of North Waziristan in September 2006 and in South Waziristan in April 2004.
The deals - intended to end violence between tribal militants and Pakistani troops - increased friction between Afghanistan and Pakistan, two key allies in the US-led "war on terror".
According to an International Crisis Group report earlier in December, Islamabad had allowed "a virtual mini Taleban-style state" to flourish on the border with Afghanistan.
The policy of "appeasement" had allowed militants to regroup and rearm and encouraged a surge in cross-border attacks in Afghanistan, the report said.
Pakistan rejected the accusations.
Analysts believe al-Qaeda leader Osama Bin Laden could be hiding in the tribal areas.