A federal appeals court ruled Tuesday that Rep. John Murtha cannot be sued for accusing U.S. Marines of murdering Iraqi civilians "in cold blood," remarks that sparked outrage among conservative commentators.

The appeals court in Washington dismissed a defamation lawsuit brought by a Marine who led the squad in the attack. The judges agreed with Murtha that he was immune from the lawsuit because he was acting in his official role as a lawmaker when he made the comments to reporters.

Staff Sgt. Frank Wuterich of Meriden, Conn., claimed Murtha damaged his reputation by saying the squad he was leading engaged in "cold-blooded murder and war crimes" in Haditha, Iraq, on Nov. 19, 2005.

At a Capitol Hill news conference in May 2006, Murtha predicted that a Pentagon war crimes investigation would show the Marines killed dozens of innocent Iraqi civilians in Haditha.

Military prosecutors have said two dozen Iraqis, including women and children, were killed in Haditha after one Marine died and two others were wounded by a roadside bomb. Wuterich is charged with voluntary manslaughter and other allegations, the only person still facing charges in the attack.

He has pleaded not guilty. He is accused of ordering his men to clear several houses with grenades and gunfire, leading to the civilian deaths.