Iraqi troops have reportedly lost control of the city of Fallujah after intense fighting with al-Qaeda supporters and Sunni tribesmen.
A security source told the BBC on Saturday that fighters linked to al-Qaeda now control the south of the city. Tribesmen allied with al-Qaeda hold the rest of Fallujah.
Late on Saturday, eyewitnesses said pick-up trucks mounted with anti-aircraft guns were in evidence on the streets of Fallujah.
The BBC says the fighting began after government troops broke up a protest camp set up by Sunni Arabs in the city of Ramadi on Monday.
Prime Minister Nouri Maliki said he makes no apology for the troops' action.
Sunnis are angered by what they perceive as discrimination by his Shia government.
The fighting in Fallujah and Ramadi has pitted government troops against the Islamic State of Iraq and the Levant (ISIL), which is affiliated with al-Qaeda, and Sunni tribesmen.