"Gunfire during celebrations can be interpreted as hostile fire and prompt return of fire," coalition radio warned.

"It blocks the reconstruction process and the flying in of humanitarian aid to certain regions."

New weapons controls announced by coalition ground forces commander Lieutenant General David McKiernan last week included a ban on celebratory fire, although he acknowledged it would be difficult to enforce as the practice was "part of the culture".

The US army has launched an investigation into the deaths of three Iraqis in the town of Samarra, north of the capital, after doctors reported that they had been killed by US troops as they rode through the streets firing in the air to celebrate a wedding.

"The initial report was that (the US troops) were receiving fire but that was an initial report and a full investigation needs to be done," said McKiernan, as he announced the inquiry Thursday.

WAR.WIRE