Suicide attackers struck near a Shiite mosque north of Baghdad and a checkpoint west of the capital on Tuesday as bombings killed at least 17 people nationwide.

The violence was concentrated in former Sunni insurgent strongholds that have seen a sharp decline in violence after local tribal leaders turned against al Qaeda in Iraq.

In the deadliest attack, a suicide car bomber struck a line of vehicles near the Anbar provincial capital of Ramadi, police said.

The blast killed three policemen and five civilians and wounded 16 others, according to police and hospital officials.