OBEIDI, Iraq - Large numbers of U.S. forces supported by helicopters gathered outside this Euphrates River village Saturday, pushing ahead with their region-wide operation to wipe out supporters of Iraq's most wanted militant.

Frightened residents retreated indoors as a large convoy of mainly Marines, backed by tanks redeployed several miles from Rommana to Obeidi, on the northern bank.

The military had no immediate comment on the Obeidi operation, but it appeared to signal a new phase in the high-profile offensive.

Operation Matador was launched last Saturday in several villages close to the Syrian border known as major routes for foreign fighters entering Iraq to battle coalition forces.

Residents said U.S. troops blocked the main road linking Obeidi with safer areas to the east outside the field of operations.

"There is fear among the residents of Obeidi, but we don't think it (the village) has any military importance. There are no fighters in the village," said one resident, 35-year-old Khalaf Ali.

The campaign, the largest since insurgents were forced from Fallujah six months ago, has killed more than 100 suspected foreign fighters allied with Jordanian-born militant Abu Musab al-Zarqawi, the military has said. Scores have also been captured.

Al-Zarqawi, a Sunni Muslim terror mastermind, has claimed responsibility for scores of bombings, assassinations and kidnappings in a bid to derail the U.S.-backed, Shiite-led government.

The offensive came amid a surge of militant attacks that have killed at least 430 people across Iraq since the government was announced April 28.

Violence continued Saturday with three Iraqi street cleaners killed when a roadside bomb exploded apparently prematurely in Dora, a southern Baghdad neighborhood, said Dr. Zaid Adil of Yarmouk Hospital.

A suicide bomber detonated his vehicle near an Iraqi police patrol in central Baqouba, north of the capital, wounding three policemen and a civilian, said police Col. Mudhafar Muhammed.

At least nine more Iraqis were killed Friday in a series of bombings, ambushes and other attacks.

Also Friday, an American soldier was killed and four others wounded when a car bomb exploded in Beiji, 155 miles north of Baghdad, the military said in a statement.

Obeidi is in Iraq's violent Anbar province, where Iraqi fighters with machine guns and grenade launchers have been setting up checkpoints in recent days, apparently in preparation to do battle.

But in Obeidi, the streets were virtually empty Saturday as residents bolted doors, remained inside and waited for a possible U.S. offensive.

Overnight, U.S. warplanes streaked noisily overhead and several loud explosions were heard in various locations throughout the region, but the source of the blasts was not immediately clear.

This remote desert region is a haven for foreign combatants who slip across the border along ancient smuggling routes and collect weapons to use in some of Iraq's deadliest attacks, according to the military.

Four Marines have been killed in fighting in western Iraq, the American military said Saturday, bringing to nine the number of U.S. personnel killed during a weeklong operation against insurgents.

The four were killed Wednesday when their troop transporter was struck by a bomb near Karabilah, a village close to the Syrian border.

Marine commanders estimate more than 100 insurgents and foreign fighters have been killed during the operation.

At least 1,613 members of the U.S. military have died since the beginning of the Iraq war in March 2003, according to an Associated Press count.

New interim prime minister, Ibrahim al-Jaafari, extended Iraq's state of emergency for another 30 days Friday throughout Iraq, except the northern Kurdish-run areas.

The state of emergency, renewed monthly since being first imposed Nov. 7 - hours before the Fallujah offensive, includes a nighttime curfew and gives security forces powers of arrest without warrants.