The British Army is facing yet another deeply embarrassing abuse scandal after pictures emerged that appear to show soldiers beating Iraqi captives.
The violent images are of eight unidentified British soldiers kicking and hitting four young men with batons and then later mocking a dead Iraqi by kicking him in the face.
As the film rolls, the soldier behind the camera can be heard laughing and shouting obscene encouragement to his colleagues.
There were calls for a swift and thorough investigation yesterday as troops currently stationed in southern Iraq steeled themselves for a backlash.
The Liberal Democrat defence spokesman, Michael Moore, said the allegations - whether true or not - increased the urgency of setting a plan to pull troops out.
"Even the suggestion of abuse weakens our position in Iraq and makes the need for a coherent exit strategy all the more urgent.
"Parliament must be told if this is a one-off, as hoped, or evidence of wider abuses."
Tony Blair promised the allegations would be investigated "very fully indeed". Speaking from South Africa, he added that the "overwhelming majority" of British forces behaved properly and did a "great job for our country and for the wider world".
The Ministry of Defence said there was little doubt as to the authenticity of the tape. It said it was taking the matter very seriously and it was now the subject of an urgent Royal Military Police investigation.
Army investigators are due to begin questioning soldiers today. It is believed that the Special Investigation Branch is focusing on a group who have left the service as well as others currently at their base in Europe. Brigadier Martin Rutledge, Adjutant General's Chief of Staff, said: "They are disturbing images. We condemn all acts of abuse and brutality and always treat any allegations of wrongdoing by our personnel extremely seriously."
Initial reports suggested that the footage was taken in Basra, southern Iraq, in January 2004 at a time of heightened tension when 20 Armoured Brigade - which is due to return to Iraq this May - was on tour.
According to the News of the World, which printed the images, the video was taken by a corporal who added a laughing commentary to the brutal beating.
He can be heard saying: "Oh yes! Oh Yes! You're gonna get it. Yes, naughty little boys. You little fuckers, you little fuckers. Die. Ha Ha." As many as 42 blows rain down on the prisoners during a minute-long sequence of the film which the paper said was handed in by a "disgusted" informant after return to their home base. He is believed to have received considerable payment.
The video was filmed at a time when troops were involved in running battles with hundreds of rioters, armed with home-made grenades, stones and sticks. It shows a grenade landing inside the compound while the black fumes of a fire just outside the perimeter blow through.
Youths hurling abuse and stones turn tail as a group of soldiers pursue them, grab four apparent youngsters and drag them into the compound. They are then seen to mete out a vicious attack. One Iraqi is heard to plead for mercy as he is punched in the head and back before being hit with a baton. Another is seen to squirm in pain as he is beaten with a baton, a third struggles as he receives similar treatment. A fourth prisoner arches in agony as a soldier, said to be a sergeant, kicks him hard between the legs.
Later in the three-minute tape, separate incidents show a man being kicked in the chest as he kneels and a soldier drawing back a blanket from a corpse before it is mocked and kicked.
Col Tim Collins, who led the Royal Irish Regiment to war in Iraq before leaving the Army after being cleared of accusations of abuse, said: "Ultimately we just need to keep everybody calm for this one and we need an investigation more swiftly than the others. We cannot have another bungled Royal Military Police investigation."
He said it would undoubtedly make life harder for those currently serving in southern Iraq, adding: "I am sure certain imams are revelling in it and using this to whip up tension.
"The bottom line is that we are looking at British servicemen, clearly acting inappropriately, but we must remember the standard set for British servicemen is the highest set for anyone in the world. These people would not have been throwing hand grenades at any other army. They would not do that to the Jordanians or the Egyptians or the Israelis because they would shoot them," he added.
A military spokeswoman in Basra insisted the situation remained quiet but acknowledged that a backlash was feared.
Catalogue of shame and humiliation
* APRIL 2004: Images of Iraqi prisoners, naked except for hoods and forced into humiliating poses, emerge. They were said to show abuse by American soldiers at Abu Ghraib prison. Six soldiers faced court martial.
* APRIL 2004: Pictures purporting to show British soldiers abusing Iraqi prisoners were published in the Daily Mirror. They turned out to be fake. A court martial against the soldier accused of taking the pictures was dropped.
* JANUARY 2005: Three British soldiers appeared at a court martial in Osnabrück, accused of abuse at Camp Breadbasket near Basra in 2003. Charges dropped against one soldier who pleaded guilty to assault, while two others were found guilty of mistreatment. They received sentences of up to two years. Photographs were taken by a soldier who was sentenced to nine months.
* JULY 2005: Seven British soldiers were charged with "negligently performing a duty" after the death of hotel receptionist, allegedly after being beaten by troops. The case is outstanding.
* SEPTEMBER 2005: Seven paras accused of murdering an 18-year-old in 2003 go on trial. In November, all seven defendants are cleared on grounds of insufficient evidence.
* JANUARY 2006: A US chief warrant officer is found guilty of killing a captured Iraqi general in November 2003 by stuffing his head into a sleeping bag and sitting on him.