At least 18 people have been killed and dozens injured during sporadic fighting in the Iraqi city of Samarra after armed men took control of several districts, military sources have said.
Government forces in the city told Al Jazeera that they believed the men were members of the Islamic State of Iraq and the Levant group (ISIL) and that the army was sending in reinforcements to face them, Al Jazeera reported.
They said the fighting was ongoing and that government warplanes were attacking rebel positions in the city, which lies 125 km north of the capital Baghdad.
ISIL, which grew from the remnants of a now disbanded al-Qaeda-allied group, has been strengthened by involvement in the war in neighbouring Syria and now holds parts of the city of Fallujah, just 65km from Baghdad.
Sources said the men entered the city in large numbers from the south with heavy weapons attached to pick-up trucks.
Bloodshed in Iraq has this year reached levels not seen since 2006 to 2007, when tens of thousands were killed in tit-for-tat sectarian attacks and the country was pushed to the brink of all-out civil war.