(Adds details, background)
BAGHDAD, Jan 5 (Reuters) - Car and roadside bombs exploded in commercial areas of Baghdad on Sunday killing at least 19 people, police and medical sources said.
The deadliest attack took place in northern Baghdad's mainly Shi'ite district of Shaab where two car bombs went off killing at least nine people and wounding 25.
No group immediately claimed responsibility for Sunday's attacks but Sunni Muslim insurgents have stepped up attacks on Iraqi security forces and supporters of the Shi'ite-led government of Prime Minister Nuri al-Maliki.
Islamist militants linked to al Qaeda and tribal fighters have taken control of Ramadi and Falluja, the main cities in the Sunni Muslim-dominated province of Anbar in a serious challenge to the government's authority. Iraqi troops and allied tribesmen are trying to retake the province.
In a separate incident, gunmen set up a fake check point on the main road between Baghdad and Kirkuk, killing six drivers, late on Saturday near Udhaim, 90 km (60 miles) north of Baghdad, police said.
(Reporting by Kareem Raheem, Writing by Suadad al-Salhy; Editing by Janet Lawrence)
Our Standards: The Thomson Reuters Trust Principles.