At least 30 people were killed Sunday when a suicide bomber targeted police headquarters in northern Iraq, officials said.
The attacker used a car bomb in the city of Kirkuk, some 250 kilometres north of the capital Baghdad, dpa reported.
On January 23, at least 35 people died in a suicide attack in a Shiite mosque north of Baghdad.
The spike in violence comes amid a widening crisis between the Shiite-led government and the country's formerly dominant Sunni minority.
Thousands of Sunni protesters have been rallying for weeks against Shiite Prime Minister Nuri al-Maliki, demanding a repeal of laws they claim target Sunnis.
Iraq has witnessed near-daily attacks since US troops withdrew in December 2011, raising fears of a return to the sectarian tensions that drove the country close to civil war in 2006 and 2007.