Continuing their massive offensive against al-Qaeda and Taliban fighters believed to be protecting Osama bin Laden's deputy Ayman al-Zawahiri, Pakistani troops arrested 100 suspects, including foreigners, from tribal areas bordering Afghanistan, the military said on Saturday.

The arrested men included Uzbeks, Arabs, Chechens and locals, Corps Commander, Peshawar, Lieutenant General Safdar Hussain said at Wana, the headquarters of South Waziristan, some 300km south of Islamabad.

Some 400 to 500 "miscreants and foreign militants" were showing stiff resistance at Palwasha and Shin Warsa areas, he said.

"These people have been here for a long, long time. They are extremely professional fighters," he said.

Hussain said the suspects tried to flee to Afghanistan in five vehicles but firing by Pakistani helicopter gunship foiled their attempt.

"Complete sealing of the border is impossible," the corps commander said, adding that there were 240 escaping points to Afghanistan.

Three foreign suspects were killed on Friday, he said, adding that a local tribe was assisting the militants.