KABUL — An Afghan soldier who shot dead four French troops has said he did it because of a recent video showing US Marines urinating on the dead bodies of Taliban insurgents, security sources told AFP.

The attack on the soldiers, who were unarmed, came on Friday at a base in eastern Afghanistan and left 15 other French troops wounded, eight of them seriously.

"During the initial interrogations by French soldiers, he told them he did it because of the video in which American soldiers were urinating on bodies," an Afghan army officer said.

The report was backed by an intelligence source and another with access to information from the Afghan ministry of defence, both of whom requested anonymity.

"In his initial confessions, he said that he was strongly motivated to kill the soldiers when he saw the video of foreign soldiers urinating on Afghan corpses," the intelligence source said.

The Afghan soldier had also referred to a video showing British soldiers allegedly abusing Afghan children, the source with access to Ministry of Defence information said.

Less than a week after news of the US Marines video broke, British military police arrested two servicemen over allegations that they abused an Afghan boy and a girl, both aged about 10, and filmed the incidents.

A spokesperson for the British embassy in Kabul said an investigation into the allegations was under way and therefore the embassy could not comment on reports of the soldier's claim.

French Defence Minister Gerard Longuet said during a visit to Kabul at the weekend that he had been told the Afghan soldier who killed the four French troops was a Taliban infiltrator.

But President Hamid Karzai did not make the same accusation in a statement Sunday, describing the attack as "an isolated and individual action".

The US video, posted online earlier this month, showed four US soldiers urinating on three bloodied corpses, and one of the men, apparently aware he was being filmed, saying: "Have a great day, buddy," referring to one of the dead.

The images conjured up previous abuses committed by US troops during the decade-long war against Taliban insurgents and top US officials scrambled to condemn the soldiers.

Told that AFP was about to run reports of the soldier's alleged confession, a spokesman for the US embassy in Kabul, Gavin Sundwall, said: "Our deepest condolences go out to France and the families of the soldiers who lost their lives in this tragic incident.

"The US embassy strongly condemns the actions depicted in the recent video which appears to show members of the US military committing disrespectful acts with the corpses of insurgents.

"Such actions are reprehensible, dishonour the sacrifices of our military and the American people, and violate the core values of both our societies.

"The Department of Defense has announced an investigation which will urgently determine the facts, and will ensure the punishment for those found guilty of wrongdoing."

The revelation that the soldier has told interrogators that he was motivated by the abuse video -- or videos -- comes after claim and counter claim over the attack.

The Taliban, who are usually quick to assume responsibility for any attack on foreign forces, have said they are still investigating.

Spokesman Zabihullah Mujahdi told AFP after Longuet's claim: "So far, it is not clear whether he was a Taliban fighter or not."

The Taliban have suggested that some of the many attacks by Afghan soldiers on their foreign counterparts are prompted purely by patriotism and anger towards the "invading enemy".

Karzai also played down the idea of Taliban involvement, failing to mention the insurgent group in a statement after his meeting with Longuet, but also apparently rejecting the "angry patriot" theory.

"The attack against French forces by an Afghan army soldier does not represent the anger of Afghan people but it is just an isolated and individual action," he said.