Pakistan’s military shelled a strategic town with tanks and artillery Thursday in the latest round of its offensive against Taliban militants in the country’s restive northwest.

Pakistan's military shelled a strategic town with tanks and artillery Thursday in the latest round of its offensive against Taliban militants in the country's restive northwest.

The heavy bombardment of Miranshah, the main town of North Waziristan tribal district, began at 6:00 am (0100 GMT), according to local intelligence and military sources.

It comes after nearly two weeks of air raids on militant targets as part of an operation aimed at wiping out longstanding militant strongholds in the area, which borders Afghanistan.

"The army has started using artillery since 6:00 am today and has bombarded Miranshah bazaar and Zafar town areas through cannon and tanks," an intelligence official in Miranshah told AFP.

Another intelligence official and a senior military official confirmed the information.

A full assault by ground troops has been expected for some days and the intensification of the shelling could indicate that it is now imminent.

Almost half a million people have fled North Waziristan in anticipation of a ground offensive, with many flooding into the nearby town of Bannu and tens of thousands crossing into Afghanistan.

The military says 361 militants have been killed in the offensive.

Resistance from the insurgents has been relatively light, leading to fears that many of them may have escaped across the rugged, mountainous border into Afghanistan.

Twelve security personnel have been killed and on Tuesday North Waziristan suffered its first suicide bombing since the operation began.

Two soldiers and a civilian died in the blast, claimed by the Ansar-ul-Mujahedin militant group, a Pakistani Taliban faction, who declared that it was the start of a counter-offensive.

Hours after that blast unknown gunmen opened fire on a passenger jet as it came in to land at Peshawar, the main city of the northwest, killing one person on board.

The army said that "12 terrorists surrendered" to security forces in North Waziristan on Wednesday.

The assault on the militant bastion of North Waziristan, long urged by Washington, was finally launched after a dramatic attack on Karachi airport which killed dozens of people and marked the end of a faltering peace process.