US Secretary of Defense Leon Panetta on Thursday condemned a video that purportedly shows US Marines urinating on the corpses of slain Taliban fighters.

“I have seen the footage, and I find the behavior depicted in it utterly deplorable,” Panetta said in a statement, saying he had ordered the Marine Corps and the commander of US and NATO troops in Afghanistan to investigate the incident.

“Those found to have engaged in such conduct will be held accountable to the fullest extent,” he said, adding the video was “shocking.”

Marine Corps headquarters at the Pentagon said: “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 video that surfaced on Wednesday earlier appeared to show American forces urinating on the bodies of dead Taliban fighters.

The International Security Assistance Force released a statement saying the desecrations “appear to have been conducted by a small group of U.S. individuals, who apparently are no longer serving in Afghanistan.”

As the Marines involved may have already rotated back to the United States the age of the video is in question.

Officials in Washington fear the video could aggravate anti-American sentiment in Afghanistan as the Obama administration hopes to end a decade-long war.

Afghan president Hamid Karzai released a statement describing the act as “completely inhumane” and called on the US military to punish the Marines.

Karzai and other senior Afghan officials expressed concern the incident could have a serious negative impact on peace negotiations between the US and Taliban.

The Taliban, however, dismissed the video saying peace talks and planned prisoner releases would proceed.

“We know that our country is occupied… This is not a political process, so the video will not harm our talks and prisoner exchange because they are at the preliminary stage,” the group said.