About 4,000 civilians have been killed in attacks across Pakistan since July 2007 [EPA]

At least six people, including two children, have been killed in a suspected suicide bomb attack in Bannu, a city in the northwest of Pakistan.

According to officials, a suicide bomber blew himself up near a police van close to a police station, in the Milad park area, on Tuesday.

Iftikhar Khan, Bannu police chief said that "the bomber came on foot and detonated himself".

"The death toll is now six. They include two boys aged seven and nine, one police official and three pedestrians. Nineteen people were injured," he said.

Bannu, where the attack occurred, lies close to Pakistan's tribal belt which borders Afghanistan, an area where al-Qaeda and Taliban fighters are believed to be based.

According to AFP news agency, the Pakistani Taliban, who frequently bomb government security forces in the northwest, have claimed responsibility for the attack.

"We will keep targeting security forces in future," Ehsanullah Ehsan, deputy spokesman of the group, told AFP by telephone from an undisclosed location.

About 4,000 people have been killed in suicide and bomb attacks across Pakistan since government forces raided the Red Mosque in Islamabad in 2007.

The attacks have been blamed on Taliban and al-Qaeda-linked networks.