An investigation has begun into claims British troops assaulted the prisoner before throwing him from a lorry.

The claims were made in the Daily Mirror which carried photos allegedly taken during the man's ordeal. Tony Blair says that if the photos are authentic this is "completely and totally unacceptable".

However the BBC's defence correspondent Paul Adams says sources close to The Queen's Lancashire Regiment believe many aspects of the photographs are suspicious.

He says they believe the pictures may not have even been taken in Iraq. They believe the rifle is an SA80 mk 1 - which was not issued to troops in Iraq.

They say soldiers in Iraq wore berets or hard hats - and not floppy hats as in the photos.

They also believe the wrong type of Bedford truck is shown in the background - a type never deployed in Iraq. Mr Blair said if there had been any abuse it was "exceptional", and should not detract from the good work being done by UK armed forces in Iraq.

However he stressed if the photos were genuine it was totally unacceptable. "We went to Iraq to get rid of that sort of thing, not to do it," he added. Military police are investigating the photos which appear to show a soldier using violence and urinating on a captive.

Pictures showing American troops humiliating Iraqi prisoners, with a hooded and naked prisoner standing on a box with wires attached to his genitals, also generated outrage earlier this week.

Armed Forces Minister Adam Ingram said there was no "culture of abuse" in the British Army despite the fact five separate inquiries into maltreatment are under way.