US forces warned residents of Fallujah through loudspeakers and leaflets today that they would detain any man under 45 years of age trying to enter or leave the rebel-held Iraqi city.
US troops also urged residents, in Arabic, to help them capture "terrorists" and warned women and children to leave the Sunni Muslim city, locals said.
The US military blocked roads round the city today after mounting air strikes overnight that local hospital sources said killed three people. The military said its warplanes struck early today in the latest of five strikes on rebel targets in Fallujah within seven hours.
Residents said troops had sealed off all roads in and out of the Sunni Muslim city of 300,000 people as US marines prepared a major offensive designed to crush the rebels before nationwide elections in January.
The hospital sources said four people were also wounded in the air strikes. Residents said five houses were destroyed. The US military said its air strikes had hit an arms cache, a rebel command post and other targets. Rebels responded with fierce mortar and rocket-propelled grenade attacks on US troops around the city, witnesses said.
US marines say they are awaiting orders from President George W. Bush and Iraqi interim Prime Minister Iyad Allawi, who is visiting Europe, before storming Fallujah and Ramadi, another Sunni city west of Baghdad with a rebel stronghold.
Most of Fallujah's population has already fled the city.