Two militants also died in the blast targeting two military vehicles from a convoy, which had stopped to deal with mechanical problems in the tribal North Waziristan region.

"It was a suicide attack," a security official said.

The injured soldiers have been taken to a military hospital nearby, he said.

Pakistan has deployed 80,000 troops on its porous border with Afghanistan to hunt militants who sneaked into tribal regions after Afghanistan's Taliban regime was toppled by US-led forces in late 2001.

Friday's attack at Bacca Khel village was the second suicide bombing in the area within a week.

On Sunday a soldier and a policeman were killed and three paramilitary soldiers were injured when a car exploded at a checkpoint, officials said.

The lone occupant of the vehicle also died in the blast in Datta Khel, 24km west of Miranshah, the main town in North Waziristan.

A man claiming to be a spokesman for pro-Taliban militants in the region said it was a suicide attack and threatened further violence against troops in the region.

Meanwhile, Pakistan police said yesterday they have arrested a top Sunni Muslim militant wanted for over 28 attacks on Shia minority that killed more than 100 people.

Habib Ullah, a member of the banned extremist group Lashkar-e-Jhangvi, was arrested Thursday in Quetta, the capital of southwestern Baluchistan province, provincial police chief Chaudhry Yaqub told AFP.