The Iraqi army intensified its shelling of Falluja on Sunday in preparation for a ground assault to regain control of the city, which has been under the control of militants for a month.

Sunni Muslim anti-government fighters, among them insurgents linked to al Qaeda, overran Falluja in the western province of Anbar on January 1, against a backdrop of deteriorating security across Iraq.

Prime Minister Nuri al-Maliki, whose Shi’ite-led government many in the Sunni minority accuse of discrimination, had held off an all-out offensive to give local tribesmen a chance to expel the militants themselves.