A video showing four United States marines urinating on the bodies of three dead Taliban fighters has provoked anger and condemnation in Afghanistan and around the world.
American officials said they feared the images could incite anti-American sentiment at a particularly delicate moment in the war effort.
At least two of the four US Marines in a video that apparently shows them urinating on the bodies of Taliban fighters have been identified, an official has said.
The group were members of the 3rd Battalion, 2nd Marines, which returned to its home base in North Carolina last autumn after a tour in Afghanistan, the official added.
He said they were identified by the US Marine Corps, which is investigating the incident, and at least some of the four were no longer in the battalion.
The footage has been condemned as "utterly deplorable" by US Defence Secretary Leon Panetta who ordered the immediate investigation.
The YouTube video was also strongly criticised by Afghanistan's president, Hamid Karzai, and the militant group itself - but the Islamists said it was unlikely to derail peace talks.
The pictures, which Sky News has blurred, show men in Marine combat gear, standing in a semi-circle over three bodies. It is not clear whether the dead were Taliban.
One of the men, apparently aware that the group was being filmed, said: "Have a great day, buddy", referring to one of the corpses. Another made a lewd joke.
Nato forces in Afghanistan also slammed the incident, saying: "This disrespectful act is inexplicable and not in keeping with the high moral standards we expect of coalition forces."
The International Security Assistance Force (ISAF) said the actions "appear to have been conducted by a small group of US individuals, who apparently are no longer serving in Afghanistan".
The Pentagon said there was no indication that it was not authentic, as the Marine Corps along with Marine General John Allen, the top commander of the Nato-led forces in Afghanistan, investigated.
