The Iraqi branch of terror network Al-Qaeda said it shot down a US helicopter that crashed in Iraq at the weekend killing 12 US troops.
In a statement posted on the Internet on Monrday, Al-Qaeda in Iraq said its "air defence units" had carried out an ambush at Bhraz in Diyala province around 3:00 pm (1730 IST) on Saturday.
"The lions of the Islamic State in Iraq succeeded in hitting a Black Hawk helicopter," it said.
"Clashes then broke out with the Crusaders. They resulted in the total destruction of two American Humvee vehicles, with all those on board killed," said the statement, whose authenticity could not be confirmed.
A senior US defence official acknowledged in Washington earlier on Monday that the UH-60 Black Hawk helicopter may have been shot down with a shoulder-fired missile.
Pentagon spokesmen said a preliminary investigation was still underway and had not yet determined what caused the helicopter to crash on Saturday northeast of Baghdad, killing all those on board.
The deadliest helicopter crash involving US soldiers dates back to November 13, 2003 when two Black Hawks collided in the Mosul region of northern Iraq killing 17 troops.