Pakistani forces have arrested a number of suspects in a major operation to flush out al-Qaeda and Taleban fighters near the Afghan border.
Tribesmen were told to hand over suspected al-Qaeda sympathisers
"There are up to 20 people arrested, and there are some foreigners among them," army spokesman Major General Shaukat Sultan told AFP news agency.
The operation, mounted in Pakistan's tribal belt, was now over, he said.
Officials would not say if al-Qaeda leader Osama Bin Laden or Taleban chief Mullah Omar were among the targets.
US forces in Afghanistan have said they are stepping up the hunt for the two men, who are believed to be in the border area.
Over the past few weeks, the Pakistani authorities have tried to persuade tribal leaders to hand over foreign fighters, most of whom fled into Pakistan's tribal belt during the US-led military operation in Afghanistan in 2001.
From dawn on Tuesday, hundreds of Pakistani soldiers backed by helicopter gunships swept through several villages in the deeply conservative South Waziristan tribal agency of North West Frontier Province.
Reports say the soldiers blew up houses believed to be used as hideouts by foreign militants.
A military statement said "weapons, ammunition and audio cassettes" as well as documents were recovered from the houses.
"The arrests... confirm that some foreigners had been living there," Major General Sultan told the Associated Press.
"We will not reveal the identity or nationality of any arrested man until the investigations are complete."
Pakistani intelligence officials said Bin Laden was not the immediate target of the current operation in the semi-autonomous South Waziristan region.
But they hope to glean clues leading to his ultimate capture.
The operation came hours after US President George W Bush pledged to hunt down al-Qaeda militants and just ahead of a visit by US Defence Secretary Donald Rumsfeld to Afghanistan later this week.
Pakistan has been a key ally of the United States since it launched its war on terror after devastating attacks on New York and Washington in 2001, for which Bin Laden is blamed.
About 500 suspects have been detained in Pakistan, and many sent to US military detention at Guantanamo Bay in Cuba.
Earlier this month, CIA chief George Tenet paid a secret visit to Islamabad to share information on the al-Qaeda leader, reports say.
Pakistan has stationed tens of thousands of troops along the porous Afghan border to hunt al-Qaeda and Taleban suspects.
Government officials vigorously deny that US troops operate on Pakistani soil.
The last time Pakistani forces were involved in a major crackdown in Waziristan, in October 2003, US helicopters patrolled the Afghan side of the border to stop suspects escaping.