The often ramshackle forces lend weight to the campaign in the lawless and mountainous region, but analysts question their effectiveness against a well-armed, well-trained and increasingly brutal insurgency.

The extremists are increasingly targeting the militias, an indication they believe them to be a threat.

Yesterday, two tribesmen were killed during an army-backed offensive against insurgents in the Bajur tribal region. Government official Jamil Khan said helicopter gunships shelled militants' bunkers, killing at least 10 people. Fifteen more suspected militants were killed in separate clashes, he said.

On Friday, a suicide bomber killed more than 50 tribesmen gathering to form an army. Eight pro-government tribesmen have been beheaded in recent days.

By encouraging the private armies, or lashkars, the government is exploiting local resentment against foreign and Pakistani extremists in the area, considered a likely hiding place for Osama bin Laden and other al-Qaeda leaders.

"These Taliban call themselves Muslims, but they have been involved in all kinds of crimes," said Malik Mohmmand Habib, a leader of the Salarzai tribe, one of the largest of at least five tribes that have formed lashkars in recent weeks. "We want them out of our area."

The lashkars have drawn comparisons with government-backed militias in Iraq - the so-called Awakening Councils - that have been credited with helping beat back the insurgency there.

But the lashkars are less organized and the tribesmen use their own, often aging, weapons. The government does not acknowledge funding the armies, but analysts suspect the leaders at least receive money.

It is also unclear how much frontline fighting lashkars are involved in. They have been photographed on patrol with military units and have reportedly been involved in several clashes, but their main task appears to be holding areas cleared of insurgents by the army.

Army spokesman Maj. Gen. Athar Abbas praised the formation of the armies, but gave few details of how they operate.

Shuja Nawaz, a prominent Pakistani security analyst, said the tribesmen were rising up because they were genuinely unhappy with the presence of the militants, but he stressed the government must quickly build roads, schools and undertake other development projects to cement the successes.

"It is a continuation of the British colonial tradition of paying off the tribes," said Nawaz, adding that historically such deals to buy loyalty often broke down.

Seeking to overcome a common perception that the fight is America's war, the government often holds up the emergence of the tribal armies as proof that locals are behind the campaign.

That task has become increasingly complicated by suspected U.S. missile strikes within Pakistani territory that are believed to have killed more than 100 people, mostly alleged militants.

The latest barrage, reported yesterday, in Pakistan's northwest killed five people. None were believed to be foreign al-Qaeda fighters, officials said.