Video Shows Beheading of American in Iraq.

CAIRO, Egypt - A video posted Tuesday on an Islamic militant Web site showed the beheading of an American civilian in Iraq, and said the execution was carried out by an al-Qaida affiliated group to avenge the abuse of Iraqi prisoners by American soldiers.

The video bore the title “Abu Musab al-Zarqawi shown slaughtering an American.” It was unclear whether al-Zarqawi — an associate of Osama bin Laden — was shown in the video, or was claiming responsibility for ordering the execution.

Al-Zarqawi also is said to have ties to terrorist groups ranging from Ansar al Islam in Iraq to Egyptian Islamic Jihad. He’s believed to be behind many attacks in Iraq, including numerous high-profile operations.

The video pictures of the execution showed five men wearing headscarves and black ski masks, standing over a bound man in an orange jumpsuit — similar to a prisoner’s uniform — who identified himself as Nick Berg, a U.S. civilian whose body was found on a highway overpass in Baghdad on Saturday.

“My name is Nick Berg, my father’s name is Michael, my mother’s name is Suzanne,” the man said on the video. “I have a brother and sister, David and Sarah. I live in … Philadelphia.”

There was no way to be certain the tape was authentic.

After reading a statement, the men were seen pulling the man to his side and putting a large knife to his neck. A scream sounded as the men cut his head off, shouting “Allahu Akbar!” — “God is great.” They then held the head out before the camera.