Officials launched a damage limitation exercise after an investigation by the German magazine Der Spiegel uncovered 4000 photographs which appeared to document abuses carried out by US troops in Afghanistan.
The magazine said it had published three graphic photographs over the weekend to document a war which had "lost sight of its original objectives."
One picture shows a US soldier casually smoking a cigarette while posing with a partially naked corpse. In a second, another member of the same unit grins as he holds up the dead man's head like a trophy. The third shows two blood-soaked bodies bound to a small pillar.
Last year, 12 US soldiers were charged with crimes ranging from murder to keeping body parts as war trophies after allegedly forming a self-styled "Kill Squad" while they were deployed in southern Afghanistan's Kandahar province.
One of the men featured in the three published photographs, Jeremy Morlock, a US Army specialist, is charged with the murder of three Afghan civilians, assaulting a fellow soldier and "wrongfully photographing and possessing visual images of human casualties."
Mr Morlock has agreed to plead guilty to murder, conspiracy and other charges and to testify against his co-defendants in return for a maximum prison sentence of 24 years.
His lawyers have said that while he might be "physically responsible" for his crimes, American leaders bear the moral responsibility for placing him "in the wrong war at the wrong time."
Mr Morlock claims that the "Kill Squad" was led by US Staff Sergeant Calvin Gibbs, who maintains the killings were legitimate attacks on would-be assailants.
Soldiers have told investigators that they passed around trophy photographs as though they were trading cards, storing them on digital devices like thumb drives. Four of the soldiers have been charged with keeping body parts, including finger bones, a skull, leg bones and a human tooth.
A US Army statement apologised "for the distress these photos cause" and said the actions depicted in them were "repugnant to us as human beings and contrary to the standards and values of the United States Army."
The US military had earlier sought to suppress the photographs amid fears they would inflame Afghan public opinion.
One security contractor in Kabul warned clients that the "graphic and extreme" nature of the pictures could incite Afghans "with anti-American sentiment."
Michael Semple, the former European Union deputy special representative to Kabul, however suggested Afghans might be more circumspect in the reactions.
Mr Semple's research into pre-2001 war crimes in Afghanistan showed Taliban and Mujahideen commanders had also collected gory trophies.
"I am sure some Afghans will look on the latest pictures as evidence that US fighters are more similar to their predecessors than they like to admit," he said. "So unless Karzai decides he really wants to play this up, this just becomes one more regrettable incident, with little bearing on either public sentiment or the overall strategy of gradually extricating US troops from the conflict."
His lawyers have said that while he might be "physically responsible" for his crimes, American leaders bear the moral responsibility for placing him "in the wrong war at the wrong time."
Mr Morlock claims that the "Kill Squad" was led by US Staff Sergeant Calvin Gibbs, who maintains the killings were legitimate attacks on would-be assailants.
Soldiers have told investigators that they passed around trophy photographs as though they were trading cards, storing them on digital devices like thumb drives. Four of the soldiers have been charged with keeping body parts, including finger bones, a skull, leg bones and a human tooth.
A US Army statement apologised "for the distress these photos cause" and said the actions depicted in them were "repugnant to us as human beings and contrary to the standards and values of the United States Army."
The US military had earlier sought to suppress the photographs amid fears they would inflame Afghan public opinion.
One security contractor in Kabul warned clients that the "graphic and extreme" nature of the pictures could incite Afghans "with anti-American sentiment."
Michael Semple, the former European Union deputy special representative to Kabul, however suggested Afghans might be more circumspect in the reactions.
Mr Semple's research into pre-2001 war crimes in Afghanistan showed Taliban and Mujahideen commanders had also collected gory trophies.
"I am sure some Afghans will look on the latest pictures as evidence that US fighters are more similar to their predecessors than they like to admit," he said. "So unless Karzai decides he really wants to play this up, this just becomes one more regrettable incident, with little bearing on either public sentiment or the overall strategy of gradually extricating US troops from the conflict."
