MIRANSHAH: A suicide bomber rammed an explosive-filled car into a checkpoint in a Pakistani tribal area Tuesday killing four security personnel, officials said.

The attack took place outside Miranshah, the main town of restive North Waziristan tribal district, bordering Afghanistan.

"Four security forces personnel were killed and eight others were wounded in the suicide bombing at Isha checkpost," a security official told AFP.

Another security official and intelligence officials based in the area confirmed the incident.

"The bomber struck his car into the security post, which exploded after the impact," the official said.

Hundreds of Islamist fighters are believed to have fled Afghanistan into Pakistan's semi-autonomous tribal areas to carve out safe havens after the US-led invasion toppled the hardline Taliban regime in Kabul in late 2001.

The region neighbours South Waziristan, the redoubt of Pakistan's chief Taliban warlord Baitullah Mehsud, who is believed to have been killed in a US drone attack earlier this month.

Recent years have seen increased clashes between Pakistani troops and Taliban militants.

The country is suffering from a deadly Islamist backlash that has killed more than 2,000 people in bomb attacks in the past two years.