U.S. and Iraqi forces are tightening their grip around the Imam Ali Shrine in Najaf, which Shi'ite militiamen have occupied for the last 20 days.
Iraqi National Guardsmen took up positions just a few hundred meters from the shrine, using loudspeakers to urge radical cleric Moqtada al-Sadr's fighters to vacate the site or face attack.
Iraq's defense minister Hazim al-Shaalan told Al-Arabiyah television that "decisive hours are drawing near," but suggested a raid would not come Tuesday.
Meanwhile, Iraq's environment and education ministers have been targeted in two separate car bomb attacks. Both officials escaped unhurt but at least five people were killed. The attacks come as U.S. forces continue to strike targets in the city of Najaf, where militants have spent the past three weeks holed up in the Imam Ali shrine.
Environment Minister Mishkat Moumim was not hurt when her convoy was bombed in the Baghdad neighborhood of Qadisiya. Her bodyguards were killed.
A group linked to wanted terrorist Abu Musab al-Zarqawi claimed responsibility for the attack on the environment minister, saying it would not fail next time.
In a second attack about the same time in Baghdad, Education Minister Sami al-Mudhaffar's convoy was targeted by a deadly roadside bomb. The minister was not injured.
Insurgents have been attempting to assassinate top Iraqi officials to destabilize the U.S.-supported interim government.