Local officials say that they suspect that the attackers, believed to al-Qaeda militants, used a remote control device to blow up the paramilitary vehicle near Miranshah, the main town in North Waziristan.

Police have arrested three suspects, although their identities have not yet been revealed by police.

Pakistani troops meanwhile yesterday ended a major operation to flush out al-Qaeda suspects and their local supporters from hide-outs in the remote region near Afghanistan that saw 72 people killed, including 17 security personnel.

The operation was launched after foreign militants killed 15 security personnel near the town of Shakai, 210 miles west of the capital, Islamabad, last Wednesday, Maj. Gen. Shaukat Sultan said.

Pakistan expects more arrests to follow its capture of a nephew of the alleged mastermind of the September 11 attacks and of another high profile foreign national, Interior Minister Faisal Saleh Hayat says.

The government announced late on Sunday the capture of an important al-Qaeda member with a $1 million (550,000 pounds) bounty on his head and the arrest of eight militants suspected in the bloody ambush of Karachi's military commander last week.

The al-Qaeda suspect was the nephew of Khalid Sheikh Mohammed, the number three leader in Osama bin Laden's al-Qaeda network and the suspected chief planner of the September 11 attacks on the United States, said Information Minister Sheikh Rashid. Mohammed was arrested near Islamabad in March last year.

Hayat described the latest capture as a "major breakthrough".

"The suspects are being interrogated," he told Reuters yesterday. "The process of dismantling the network has speeded up. We expect more arrests will take place."

He said he believed the militants had attended an al-Qaeda training camp in South Waziristan, 400 km (250 miles) southwest of Islamabad, where the army is mopping up after a fierce offensive last week near tribal region's main town of Wana.

"They are linked to Wana, with the training camp and the firing range of al Qaeda. It was a main centre and well established transit point," he said.