Two US pilots were killed when their helicopter crashed in west Baghdad last night, the US military said today.
"There was no hostile fire involved," it said in a statement, without giving details.
Dozens of US-led forces have been killed in helicopter crashes since the invasion of March 2003, some in accidents and some after being fired on by insurgents with shoulder-fired missiles or small arms.
In some of the worst incidents, two US Black Hawk helicopters collided under fire in Mosul in November 2003, killing 17 soldiers, a week after another Black Hawk was shot down killing six.
A Black Hawk was shot down near Falluja in January 2004, killing all nine on board.
In January this year, a US transport helicopter crashed close to the Jordanian border in Anbar province, western Iraq, killing 30 Marines and one sailor.
Faced with dangerous roads and vast tracts of desert, the military uses helicopters as its main means of transport to move troops and supplies between bases dotted around the country.