Civilians pass a destroyed car in the a car bomb explosion in southwestern Baghdad, Iraq. Two car bombs in southwestern Baghdad killed and wounded people and police officers late on Friday night according to Iraqi police and hospital officials. Picture: Karim Kadim/AP

Baghdad - Thirty-five people were killed and 33 injured in a string of suicide bombings claimed by the Islamic State extremist militia in two Iraqi cities, police said Saturday.

The overnight attacks involving car bombings targeted security checkpoints in the capital Baghdad and the southern city of Basra, they added.

Islamic State claimed responsibility for the four bombings in online statements.

In recent months, Islamic State has stepped up its attacks in different parts of Iraq in a bid to distract attention from an ongoing US-backed campaign to dislodge it from its last key stronghold of Mosul in Iraq.

On February 19, Iraqi forces started a major offensive to wrest back the western section of Mosul from Islamic State, almost a month after they recaptured the eastern part of the city.

Over the past weeks, government forces have retaken several neighbourhoods in western Mousl, squeezing the Islamic State militants into small-but-densely populated parts of the city.

Islamic State seized Mosul, Iraq's second-largest city, in a blitz in mid-2014.