A suicide bomber today killed at least nine people on a packed bus outside an Iraqi Army checkpoint in northern Iraq, an area where American forces have been focusing more attention in a bid to tackle al-Qaeda insurgents.

The explosion occured as soldiers at the checkpoint asked to see the identity cards of passengers on the bus, which had been travelling towards the Syrian border, according to an Iraqi officer based on a camp nearby.

"When the bomber saw that he was surrounded by Iraqi Army guys he decided to blow himself up," said Captain Farrid Hazem, from al-Kisik Base, about 45 miles from Mosul, Iraq’s third largest city. One Iraqi soldier was among the wounded, he added.

Offering a slightly different version of events, the US military said that the explosion took place outside the vehicle, blaming al-Qaeda in Iraq (AQI) for the carnage.

"During a stop at a routine checkpoint, the Iraqi Army searched passengers for their identification cards. The suspected AQI suicide bomber exited the bus and then detonated the bomb," it said, putting the death toll at eight.

In yet another account, a second Iraqi army officer said that the bomber had instructed the driver of the bus, loaded with 45 passengers, to divert from his route to avoid army checkpoints. When the driver refused the bomber detonated his explosives belt.

Attacks in the northern province of Ninevah, in which Mosul is the capital city, have been bucking the trend of an overall decline in bloodshed across the rest of the country following a US surge of troops last year. American commanders believe that al-Qaeda insurgents have been pushed north by the increase of troops in Baghdad and the surrounding belts.

The number of American and Iraqi troops in Nineveh has been increased since the start of the year, with soldiers setting up more outposts inside Mosul to develop a permanent presence in the city of some 1.6 million people.

Bomb-scarred buildings, pitted roads and fields of mud and rubbish, however, are a constant reminder of the violence that has shaken Mosul over the past five years. People are crying out for basic services such as water and electricity, while unemployment is as high as 70 percent in certain areas.

Major Gary Dangerfield, a spokesman for the 3rd Armoured Cavalry Regiment in Mosul, said in response to the attack: "Today’s events are a clear indication that insurgents have no productive plan for the future of Iraqi citizens, just one committed to stealing their future."

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