The Iraqi army shelled the western city of Fallujah with mortars overnight to try to wrest control from Sunni Muslim militants and tribesmen, killing at least eight people.

Fallujah has been held since Monday by militants linked to al-Qaeda and by tribal fighters united in their opposition to Prime Minister Nuri al-Maliki, in a serious challenge to the authority of his Shi'ite-led government in Anbar province.

Doctors in Fallujah said 30 people were wounded in the shelling. Al-Qaeda's Islamic State of Iraq and the Levant has in recent months tightened its grip in the Sunni-dominated desert province near the Syrian border in a bid to create a new Islamic state.