US soldiers
US soldiers in Afghanistan. Reuters

(REUTERS) -- The Marine Corps was investigating a video showing what appear to be American soldiers in Afghanistan urinating on the bodies of dead Taliban fighters.

The video could aggravate anti-American sentiment in Afghanistan after a decade of a war that has seen other cases of abuse. The Marine video release comes at a sensitive moment, with Washington trying to promote Afghan reconciliation as US troops gradually withdraw from the country.

The video, which was posted on YouTube and other websites, shows four men in camouflage Marine combat uniforms urinating on three corpses.

One of them jokes: Have a nice day, buddy. Another makes a lewd joke.

While we have not yet verified the origin or authenticity of this video, the actions portrayed are not consistent with our core values and are not indicative of the character of the Marines in our Corps, the Marines said in a statement. This matter will be fully investigated.

Two US military officials, speaking on condition of anonymity, said the video appeared to be authentic at first look but Reuters could not independently verify the video or its source.

A Muslim civil rights group in the United States condemned the alleged desecration of corpses in a letter to Defence Secretary Leon Panetta.

Any guilty parties must be punished to the full extent allowed by the Uniform Code of Military Justice and by relevant American laws, the Council on American-Islamic Relations said.

Strong reaction to the story spread on military-related Web sites, including on Stars and Stripes, the leading Defense Department-authorized news publication.

I'm a vet I know what it's like to hold hate for your enemy. Not saying what they did is right by any means what so ever. But never record such a thing and never post it on the internet, wrote one reader, warning the Taliban may use it as an excuse to mistreat American prisoners.

Lock them up, wrote another.

The US military has been prosecuting soldiers from the Army's 5th Stryker Brigade on charges of murdering unarmed Afghan civilians while deployed in Kandahar province in 2010.

In that case, photographs published in March by two magazines - Der Spiegel and Rolling Stone - showed soldiers posing with the bloodied corpse of an Afghan boy they had just killed.

At the Pentagon, Capt. John Kirby said the defense department was deeply troubled by the video.

Whoever it is, and whatever the circumstances - which we know is under investigation - it is egregious behavior and unacceptable for a member of the military, said Kirby, a Pentagon spokesman.

Ambassador Marc Grossman is due to visit Afghanistan and Qatar next week for talks with the Afghan and Qatari governments.