The use of the tactic has raised fears that Taliban fighters from the northwest of the country are spreading their campaign against the government further afield.

The Pakistani military has widened an offensive against fighters opposed to the government  from the North West Frontier Province to neighbouring South Waziristan in recent days, targeting bases reportedly used by Baitullah Mehsud, leader of the Pakistani Taliban. 

"It may be a sign of desperation at a time when they are coming under tremendous pressure because of the offensive," Talat Masood, a retired Pakistani general and defence analyst, said.

"It also shows they want to widen the conflict and hit the army wherever it is."

'Hurting and reacting'

Shah Mehmood Qureshi, Pakistan's foreign minister, said that the attack would not distract security forces from the offensive in the northwest.

"The militants are hurting and they are reacting. And this is a reaction to the successful operations we've had in Waziristan and we've had in the Malakand division," he said in an interview with the Reuters news agency.

"But these odd attempts will not distract us. We are focused and we know what has to be done."

Pakistan and India have fought two of their three wars since they gained independence from British rule in 1947 over Kashmir.

Separatist fighters have carried out attacks against security forces on the Indian side of the Line of Control that divides the two parts of of the region for more than two decades.

But the Pakistani-controlled area has been largely peaceful.

India and Pakistan both claim the whole of predominantly Muslim Jammu and Kashmir region.

About 10 million people live in the Indian-administered side and three million in the Pakistan-administered side.