A suicide bomber blew himself up in Pakistan’s northwestern city of Peshawar on Wednesday, killing at least six people including a senior police officer.

A suicide bomber blew himself up in Pakistan's northwestern city of Peshawar on Wednesday, killing at least six people including a senior police officer, Agence France Presse reported.

The blast ripped through a congested part of the city, which lies close to Pakistan's lawless tribal areas and is frequently hit by bombings, leaving blood and body parts in the street.

Police official Badshah Khan said the bomber, who was on foot, targeted the vehicle of senior investigator Hilal Haider, killing him and a number of his colleagues.

Hospital officials and senior administration official Habibullah Arif said more than 30 people were wounded and some were in critical condition.

Peshawar is the capital of Khyber Pakhtunkhwa province and a gateway to the semi-autonomous tribal belt along the Afghan border, where Al-Qaeda and Taliban extremists have strongholds.

There was no immediate claim of responsibility for the attack, which came as news of US President Barack Obama's re-election emerged. Washington is a key focus for the anger of militants in Pakistan.

Suicide and bomb attacks blamed on extremist insurgents have killed more than 5,200 people since July 2007 across Pakistan.