A suicide car bomber killed at least 12 people in an attack at a checkpoint near a police training academy in northeastern Baghdad on Sunday, police and hospital sources said.

They gave death tolls ranging from 12 to 17, while estimates of the number of people wounded varied between 18 and 23.

I can see body parts scattered on the ground and boots and berets covered with blood. Many cars were set ablaze, said a policeman working at the academy on Palestine Street in northeast Baghdad.

Security services in the Baghdad operations centre, which provides more conservative estimates of casualties, said one person was killed and six people were wounded in the attack at the police academy's rear entrance.

The attack breaks a period of relative calm that accompanied an easing in a political crisis pitting Shi'ite Prime Minister Nuri al-Maliki against senior members of the Sunni-backed Iraqiya political bloc.

Tensions rose on Thursday, however, when a panel of judges detailed 150 attacks they said were carried out by death squads under the command of Sunni Vice President Tareq al-Hashemi. Maliki sought Hashemi's arrest in December, sparking the crisis.

(Reporting by Kareem Raheem, Ahmed Rasheed and Suadad al-Salhy; writing by Francois Murphy, Editing by Mark Trevelyan)