Rescue workers inspect the devastation following car bombings in the northern city of Kirkuk [AFP]

At least seven people have been killed in three near-simultaneous car bombings in the northern Iraqi city of Kirkuk.

Dozens of bystanders were also injured as the blasts, which detonated around 10:25am local time, tore through the offices of Kurdish internal security forces - as well as targeting a police patrol and a senior police officer's convoy.

Police officials were quick to blame an armed group and promised a strong response.

'"We are certain that this terrorist group, Ansar Al-Islam, is behind this attack," Major General Jamal Taher Bakr, the city police chief, said.

"Our security forces will punish that group, because they have targeted all  the people of Kirkuk. They are trying to raise sectarianism but they will fail, as they failed before."

A woman, a child and two policemen were believed to be among the dead in the city, 240km north of Baghdad, which has been the focus of a bitter land dispute between Iraq's central government and its autonomous Kurdish region.

Car bombs

The police chief said the attacks included a car driven by a suicide attacker which struck the office of Asayesh forces - Kurdish internal security - loyal to the Kurdistan Democratic Party of Kurdish regional president Massud Barzani.

The second blast, which reportedly targeted a police patrol, detonated in the same residential neighbourhood, in the west of the city. Cars and homes were severely damaged in the attacks, and firefighters struggled to contain the subsequent blazes. 

The injured are understood to be undergoing treatment at Kirkuk General and Azadi hospitals.

Nearly 200 people died last month in bomb attacks in the Kirkuk region, which sits on rich oil reserves, showing the district remains a tinderbox as the US military prepares to withdraw its remaining troops from the area.