Taliban suicide bomber targeted a Shia procession in the Pakistani garrison city of Rawalpindi killing at least 23 people and injuring 68 others in the latest of a slew of attacks against the minority community in the country during the Islamic month of Muharram.

The bomber blew himself up when people tried to prevent him from entering the procession that was on its way to an imambargah (Shia prayer hall) shortly before midnight last night, officials said today.

They said the devastating attack left 23 people dead and 68 injured.

Shia processions organised during the month of Muharram have often been targeted in the past and two blasts, including one involving a suspected suicide bomber, outside a Karachi imambargah last evening killed two persons and injured 16 others, including media representatives and security men.

The suspected bomber's explosives went off when his motorcycle collided with an auto-rickshaw outside the Karachi imambargah.

As rescuers and security personnel gathered at the site, an improvised explosive device went off, injuring more people.

The Pakistani Taliban claimed responsibility for the attacks in Rawalpindi and Karachi.

A Taliban spokesman told the media that the militants had a "war of belief" with the Shias.

Branding the minority sect as "blasphemers," the spokesman said the Taliban would continue attacking them.

Separately, four policemen, including a senior officer, were gunned down by militants at Bannu in the northwest yesterday while five persons were killed and 20 injured when a security forces vehicle was targeted with a roadside bomb in the southwestern city of Quetta.

The attacks prompted authorities to beef up security for the Developing Eight (D-8) Summit beginning here today.

Leaders from Iran, Egypt, Malaysia, Nigeria, Turkey, Bangladesh and Indonesia are attending the meet, which Pakistan is using as an event to position itself as a key player in the Islamic world.