Pakistani tribesmen marched into the hills near the Afghan border on Sunday to flush out al-Qaida fighters and their local supporters after they refused to surrender.
Around 2,000 tribesmen, armed with assault rifles and other light weapons, set out on foot for Parvazaragh, around 20 miles from Wana in South Waziristan, to hunt the foreign militants holed up in their territory.
The government set a deadline of April 20 for tribal elders to hand over the al-Qaida fighters, thought to be Chechens, Arab and Uzbeks, and the tribesmen sheltering them.
But elders failed late last week to persuade militants and their protectors to surrender peacefully.
"We have waited long enough. Now it is the time for action," said Malik Bakhan, a pro-government elder told a gathering of up to 6,000 tribesmen in Sholam, near Wana.
Tribesmen expect stiff resistance from the militants, who last month battled around 5,000 Pakistan troops for several days. More than 100 people died, but no top militant was captured.
Pakistani authorities, who govern the semi-autonomous tribal region by special laws, have put pressure on the tribes to help hunt down militants.
"These people are bringing misery and trouble to our people," said Malik Khadim, another tribal elder.
"If the wanted men are not arrested or killed, action will be taken against those tribes who fail to do their duty."
Witnesses in Wana -- 238 miles southwest of the capital Islamabad -- saw several bands of tribal warriors moving out to other parts of South Waziristan in the hunt for militants.
The army has also sent more troops to Wana in recent days.
President Pervez Musharraf, a key ally in the U.S.-led war on terror, has vowed to clear foreign militants from the tribal areas, where they pose a danger to the Afghan government.
Musharraf also blamed militants with links to tribal areas for terror attacks across Pakistan, including two attempts on his life in December.
Tension has gripped Wana and other parts of South Waziristan after homes and property were destroyed during the last month's intense fighting.