WASHINGTON — The Web site WikiLeaks.org released a graphic video on Monday showing an American helicopter shooting and killing a Reuters photographer and driver in a July 2007 attack in Baghdad.

A senior American military official confirmed that the video was authentic.

Reuters had long pressed for the release of the video, which consists of 38 minutes of black-and-white aerial video and conversations between pilots in two Apache helicopters as they open fire on people on a street in Baghdad. The attack killed 12, among them the Reuters photographer, Namir Noor-Eldeen, 22, and the driver, Saeed Chmagh, 40.

Reuters employees were allowed to view the video on an off-the-record basis two weeks after the killings, but they were not allowed to obtain a copy of it. The news organization said its Freedom of Information Act requests were not approved.

At a news conference at the National Press Club, WikiLeaks said it had acquired the video from whistle-blowers in the military and viewed it after breaking the encryption code. WikiLeaks released the full 38-minute video as well as a 17-minute edited version.