by Nasir Jaffry

RAWALPINDI, PAKISTAN - An apparent suicide bomber riding a motorcycle killed up to six people when he rammed a bus carrying staff from a Pakistani government department in the garrison city Rawalpindi on Thursday.

The blast ripped through one of the most congested junctions in the heart of the huge sprawling city that headquarters Pakistan's powerful military and lies adjacent to the capital Islamabad.

There was no immediate claim of responsibility but many recent bombings in Pakistan have been seen as attempts to avenge a two-month military offensive against the Taliban that has been welcomed by the government's US ally.

"In the bus there were 25 to 30 staff members of a government department," Nasir Durrani, a regional police officer in Rawalpindi, told reporters live on Pakistani television stations.

"Suddenly a motorcyclist hit it near the petrol tank. Five to six are martyred and some 15 to 16 injured," he added.

"From the condition of the destroyed motorcycle, it was apparently a suicide attack," Durrani said pointing to the discovery of body parts.

One side of the bus was completely damaged, said an AFP correspondent. Pieces of broken glass, blood, flesh, human hair and bone fragments scattered the road, as a strong stench of blood and explosives hung in the air.

"We have initial reports of four to five dead and 20 injured," city police chief Rao Iqbal told AFP.

"All the injured have been taken to hospital. This bomber was on a motorbike and he struck the bus with his bike at the busiest traffic signal when the traffic light was red," he added.

"According to our assessment he had three to four kilograms (six to eight pounds) of explosive material. Several other vehicles were also damaged. This bus was hired for government officials."

Pakistani police spoke out against what they termed new militant tactics targeting a moving vehicle with security forces on a heightened state of alert in major cities in recent weeks.

"There is high state of alert. All vehicles are being checked at various checkpoints and sniffer dogs are also being used, but motorcycles were not checked in similar manner," Durrani said.

The attack happened in the same area where a suicide bomber blew himself up on a motorbike killing 14 people near a restaurant and taxi rank on March 16.

About 2,000 people have died in bombings since July 2007 and the United States has put Pakistan at the heart of its war against Al-Qaeda and efforts to stabilise Afghanistan, welcoming a military push to clear out Taliban havens.

Some of the worst attacks have been blamed on Pakistani Taliban warlord Baitullah Mehsud, who has Pakistani and US bounties on his head, and is the focus of an expected ground offensive in South Waziristan on the Afghan border. --AFP