Shia militants have clashed with Iraqi police in the holy city of Najaf, leaving at least five people dead and shattering a short-lived truce.
The Shia militants have been holding Najaf's sprawling cemetery
A policeman and several militants were killed, while 29 people including civilians were reported wounded.
The fighting came despite a truce agreed on 4 June between the Mehdi Army militia of Shia cleric Moqtada Sadr and the US-led coalition.
Iraqi police said US troops were not involved in the latest clashes.
The Shia militants reportedly attacked a police station late on Wednesday, using machine guns and rocket-propelled grenades.
Earlier, police had tried to arrest suspected thieves, according to witnesses.
Under the truce, Moqtada Sadr had agreed to withdraw his fighters from the Islamic shrines in Najaf and the nearby holy city of Kufa.
Iraqi police returned to the streets of Najaf on 5 June, while US forces pulled out to their base on the edge of the city.
The Mehdi Army's uprising against the US occupation began in April and the militia suffered heavy casualties in clashes with US forces before the truce was negotiated.