The U.S. Marine Corps said Wednesday it is investigating an Internet video that showed several soldiers were urinating on the bodies of Taliban fighters killed in Afghanistan.

"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 Corps said in a statement, promising the matter "will be fully investigated."

In the video, four men in U.S. camouflage combat uniforms appear to be urinating on the corpses of three dead Taliban fighters. One of the soldiers joked: "Have a nice day, buddy."

It remained unclear who shot and posted the video on the Internet.

Pentagon spokesman John Kirby said the video is "deeply troubling," because it depicts "egregious behavior."

The Council on American-Islamic Relations, a U.S. Muslim civil rights group, condemned the desecration of corpses in a letter sent to U.S. Defense 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 group said in the letter, which was also sent to media organizations.