About 20 people, including foreigners, were arrested when Pakistani troops, backed by helicopter gun ships and artillery, launched an operation to track down Al Qaeda and Taliban fighters in the rugged tribal terrain in the south Waziristan region bordering Afghanistan.

"In an early morning operation on Tuesday, we have arrested 15 to 20 people," Information Minister Sheikh Rashid Ahmad said adding there is no information on Al Qaeda leader Osama bin Laden and Taliban leader Mullah Omar.

About the foreigners, he said, "We do not know which county they belong to or who they are. We are investigating."

The military issued a statement saying troops recovered weapons, ammunition and audio cassettes during the operation. Certain documents, including passports, recovered from houses, confirmed the presence of foreigners.

Defence spokesman Maj Gen Shoukat Sultan told reporters that security forces targeted Zarakai village in Azam Warsik area, believed to be a sanctuary of Taliban and Al Qaeda fugitives who fled Afghanistan after the US-led operation against them two years ago. The government had received a tip-off about the presence of militants who later ignored a February 20 deadline to surrender.

Local television networks reported that troops conducted house-to-house searches. Sultan said the operation was being conducted by Pakistani troops alone. He did not have information on whether US and Afghan troops had been mobilised on the Afghan side.