At least 30 people have been killed in a double bombing targeting the offices of a Kurdish political party in the northern Iraqi town of Tuz Khurmato, local officials and medical workers said.
Security sources said a car bomb blew up at a checkpoint on Monday near the local headquarters of the Patriotic Union of Kurdistan party, before a truck packed with explosives was detonated beside a wall.
About 185 people were injured in the blasts that also destroyed many buildings in the area.
The attack came a day after 18 people died in twin blasts targeting the party's offices in the town of Jalawla.
The rebel group Islamic State in Iraq and the Levant said it carried both attacks.
Wiitnesses and victims told Reuters of huge plumes of smoke and dozens of bodies after the attack on Monday.
Tuz Khurmato is about 170km north of the capital Baghdad, and lies in territory which both the federal government and the autonomous Kurdistan Regional Government claim as theirs.
Both are a target for Sunni rebels who in recent days overran two major cities, occupied a university campus in western Iraq and set off a dozen car bombs in Baghdad.
Nearly 800 people were killed across the country in May - the highest monthly toll this year so far - and last year was Iraq's deadliest since violence began to ease from a peak in 2006-07.