Four school children are among 19 people killed in a suicide car bombing in north-west Pakistan.

The attacker rammed a pickup into a police station in Lakki Marwat town, in Khyber Pakhtunkhwa province.

Books and a school bag could be seen in the wreckage. Reports say the dead included 11 police officers.

More than 100 people died in attacks on Shia Muslims last week. The Pakistani Taliban says they carried out the attacks.

After a lull in violence during the recent floods, Pakistan's militant networks seem to be back in business.

More than 100 people have been killed in bloodshed over the last six days. Initially, the attacks have been sectarian, targeting minority sects.

But with Monday's bombing, the militants once again appear to have the security agencies in their crosshairs.

This comes after a de facto truce between the two sides since Pakistan's army announced in January 2010 that it would not carry out any new offensives against the Taliban.

Although the army has maintained pressure in the areas which it wrested from them, the militants have used the time to regroup and replenish their strength.

The Pakistani Taliban's leadership, including supreme commander Hakimullah Mehsud, is still active.

The militants had said they would not carry out any attacks in the flood-affected areas, and with the waters now receding, more attacks can be expected across Pakistan.

More than 40 people were wounded in Monday's blast at Lakki Marwat.

The bomber reportedly struck a school van before ramming the rear wall of the police station; the building collapsed.

A neighbourhood shop and mosque were also damaged.

Destruction

Rescue workers and police officials dug through the rubble to reach those trapped.

Police sub-inspector Ameen Khan Marwat was pulled out alive.

"All the morning staff were there because they had not yet left for their duties," he said.

"Some were still lying around, others were getting ready for duty when the blast occurred.

"Suddenly there was dust and darkness all around, and after that we had no idea where anyone was or what had happened to the others. It was sheer destruction all over."

As well as the four schoolchildren, the dead included a retired teacher, reports the Associated Press of Pakistan.

"Seventeen dead bodies and 45 injured have been brought to our hospital," Dr Ghulam Ali, of Lakki Marwat's main hospital, told the news agency AFP by telephone.

The Pakistani Taliban claimed they carried out the attack, in a telephone call to the AP news agency.

They said that police were targeted because they had been encouraging residents to set up militias - known locally as lashkars - to fight the militants.

The Taliban pledged to carry out more attacks unless the militias disbanded.

Huge bombs

Prime Minister Yousuf Raza Gilani strongly condemned the latest bombing.

"It goes to show that the terrorists have no creed except bloodshed and chaos, and are desperately carrying out their agenda regardless of the precarious conditions," he told a meeting of provincial officials.

"I want to stress today that we shall never let their nefarious designs succeed and will eliminate them."

Pakistan's security forces have been fighting Taliban and al-Qaeda militants based in the north-west of the country for several years. Members of the Afghan Taliban are also based in the region.

Last week, more than 100 people were killed in suicide bombings at Shia minority processions in Pakistan. On Friday, an attack in Quetta killed 73 people, two days after blasts killed 35 people in Lahore.

The town of Lakki Marwat has previously been the scene of huge bomb attacks by militants, mainly on security personnel and tribesmen allied to them.

The police chief of Lakki Marwat district was killed in a suicide bombing several months ago.

The biggest attack in the town was on New Year's Day 2010, when more than 100 people died after a suicide bomber blew up a pick-up truck, after crashing into a crowd watching a volleyball match.

Nearly 9,000 people died across Pakistan in militant-related violence between 2007-09, according to the country's independent human rights commission.