Media playback is unsupported on your device Media caption Fears of 'Taliban video' backlash

Afghan President Hamid Karzai has condemned a video that appears to show US Marines urinating on the bloodied corpses of several Taliban fighters.

The Taliban has also criticised the video as "shameful" but said it would not derail attempts at peace talks.

The US military is investigating the authenticity of the video and the Marine Corps said the actions were not consistent with its core values.

The origin of the video is not known, nor is it clear who posted it online.

The footage shows four men in military fatigues appearing to urinate on three apparently lifeless men. They have brown skin, bare feet and are dressed in loose-fitting outfits. One appears to be covered in blood.

A man's voice is heard saying: "Have a great day, buddy."

The men in military fatigues seem to be aware they are being filmed.

'Wild action'

In a statement, President Karzai's office said: "The government of Afghanistan is deeply disturbed by a video that shows American soldiers desecrating dead bodies of three Afghans.

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"This act by American soldiers is simply inhuman and condemnable in the strongest possible terms. We expressly ask the US government to urgently investigate the video and apply the most severe punishment to anyone found guilty in this crime."

Taliban spokesman Qari Yousuf Ahmadi told the BBC that this was not the first time Americans had carried out such a "wild action" and that Taliban attacks on the Americans would continue.

But a different Taliban spokesman, Zabihullah Mujahid, said the video "is not a political process, so the video will not harm our talks and prisoner exchange because they are at the preliminary stage".

Last week the Taliban said they were working to set up a political office, possibly in the Gulf state of Qatar, that could help jump-start peace talks with the Afghan government and its Western allies.

Washington has been considering releasing several Taliban prisoners from the Guantanamo Bay jail as a confidence-building measure, Associated Press news agency says.

The video has not yet circulated widely in Afghanistan but there are fears of a backlash against the foreign presence in the country once it does.

"The US soldiers who urinated on dead bodies of Muslims have committed a crime," Kabul resident Feda Mohammad told Reuters news agency.

"Since they've committed such a crime, we don't want them on our soil anymore."

Afghan Member of Parliament Fawzia Kofi said ordinary Afghans, no matter how they felt about the Taliban, would be upset by the video.

"It's a matter of a human being, respect to a human being," she told the BBC.

The actions portrayed are not consistent with our core values and are not indicative of the character of the Marines in our Corps US Marine Corps

"I believe that the brutal acts that the Taliban did here during their government and even now is condemned by Afghans. So is watching a brutal act by international forces. We condemn that as well," she added.

The Taliban are known for applying a ruthless brand of Islamic Sharia law in areas they control and have carried out many suicide bombings and attacks which have killed civilians.

Investigation

The US military said it was "deeply troubled by the video" and was investigating it.

Marine Corps headquarters at the Pentagon said in a statement: "The actions portrayed are not consistent with our core values and are not indicative of the character of the Marines in our Corps. This matter will be fully investigated.''

The Nato-led International Security Assistance Force (Isaf) said it "strongly condemns the actions depicted in the video, which appear to have been conducted by a small group of US individuals, who apparently are no longer serving in Afghanistan".

In a separate case, the US military has been prosecuting five soldiers from the army's 5th Stryker Brigade who are accused of killing Afghan civilians during their deployment in Kandahar province in 2010.

The US has about 20,000 Marines deployed in Afghanistan, based mostly in Kandahar and Helmand provinces. In total, about 90,000 US troops are on the ground in Afghanistan.

The US and its partners in Afghanistan have said they plan to hand over security of the country and withdraw combat troops by the end of 2014.