"Four marines assigned to 1st Marine Expeditionary Force died in Al Anbar Province Saturday while conducting security and stability operations," a US military statement said.

A US military spokesman later said the attack was near Fallujah, west of Baghdad.

The latest casualties bring to 657 the number of US troops killed in action in Iraq since the start of the US-led war in March 2003, according to figures by the US Defense Department.

WAR.WIRE