The Ministry of Defence has launched an investigation into allegations that British soldiers have been pictured torturing an Iraqi prisoner.
The paper claims British soldiers handed over the photos
The photographs, obtained by the Daily Mirror newspaper, show a suspected thief being beaten and urinated on.
Downing Street swiftly condemned the pictures, echoing concerns it earlier expressed over images of Iraqi prisoners being abused by US troops.
The pictures involving American troops provoked international outrage.
They included a hooded and naked prisoner standing on a box with wires attached to him.
US President George W Bush vowed that those responsible would be "taken care of".
"I shared a deep disgust that those prisoners were treated the way they were treated. I didn't like it one bit," he said.
The people who are alleged to have carried out the abuse "do not reflect the nature of men and women we sent overseas", Mr Bush added.
Tony Blair's official spokesman said this behaviour directly contravened the US-led coalition's policy.
Later on Friday Downing Street responded to the pictures printed in the Mirror.
A spokesman said: "We expect the highest standards of conduct from our forces in Iraq despite the difficulties they face."
The UK's top general, Sir Mike Jackson said if the allegations proved to be true, the members of the Queen's Lancashire regiment, involved were not fit to wear the uniform.
Defence Minister Adam Ingram told the Mirror the behaviour was "clearly unacceptable".
He added: "We have, of course, launched an immediate investigation."
BBC defence correspondent Paul Adams said the MoD was in a "tailspin" over the news, which threatened the British mission to win Iraqi "hearts and minds".
The Mirror says the pictures were handed over by British soldiers who claimed a rogue element in the British army was responsible for abusing prisoners and civilians.
Speaking on condition of anonymity, the soldiers told the paper no charges were brought against the
They allege during his eight-hour ordeal he was threatened with execution, his jaw broken and his teeth smashed.
After being beaten and urinated on, he was driven away and
dumped from the back of a moving vehicle, the soldiers claimed, unaware if he was dead.
The reason for making the photos public was, they said, to show why the US-UK
coalition was encountering such fierce resistance in Iraq.
One told the paper: "We are not helping ourselves out there. We are never
going to get them on our side. We are fighting a losing war."
In a press conference, Sir Mike Jackson, Chief of General Staff, said: "If proven, not only is such appalling conduct clearly unlawful but also contravenes the British Army's high standards of conduct.
"The allegations are already under investigation.
Sir Michael said most UK soldiers were commendable
"Again, if proven, the perpetrators are not fit to wear the Queen's uniform and they have besmirched the Army's good name and conduct."
But he said the Army should not be judged on the behaviour of a few soldiers who had let down the good work of tens of thousands of others.
Ahmed al-Sheik, editor-in-chief of Arab TV news channel, said the photographs would outrage Arabs around the world.
"These scenes are humiliating not only to the Iraqis, but to every Arab
citizen around the world," he told BBC Two's Newsnight.
Liberal Democrat defence spokesman Paul Keetch called on Defence Secretary Geoff Hoon to come to the Commons to make a statement on the allegations.
And Donald Anderson, the Labour chairman of the House of Commons Foreign Affairs
Select Committee, said the pictures could hit the Army's morale.
This is not the first incidence of alleged abuse by British troops in Iraq.
Ten claims of torture have been investigated and five inquiries are ongoing, including one in which soldiers of the Queen's Lancashire Regiment, based in Catterick, North Yorkshire, have been questioned about the alleged killing of an Iraqi.