At least five people have been killed and 20 others wounded in a car bomb explosion outside an Iraqi police station south of Baghdad.
The blast occurred in the town of Mahawil near Hilla, about 70 km (40 miles) from the Iraqi capital.
In the past year Iraqi insurgents have repeatedly targeted security forces, whom they view as collaborators supporting US troops.
The blast came as fighting flared up again in the holy city of Najaf.
US troops and Iraqi security forces fought fierce battles there with supporters of the radical Shia cleric Moqtada Sadr.
The Najaf governor requested back-up from US marines after the main police station was attacked overnight, the US military said.
The marines called the attack a violation of a June ceasefire agreement that was designed to put an end to an uprising by Mr Sadr's militia.
In the Mahawil attack, a suicide bomber drove a minibus up to the police station and detonated it, an official said.
Insurgents have stepped up attacks against Iraqi security forces in recent weeks.
One of the worst such attacks occurred on 28 July, when nearly 70 people were killed in a suicide bombing outside a police base in Baquba north of Baghdad.
On Sunday five people were killed in another suicide bomb blast at a police station in the northern city of Mosul.