"At around 2:00 pm (1000 GMT) a car drove up to the Sabtiyah checkpoint and, before the national guardsmen could search it, the driver blew up the vehicle," said Captain Sabah Nasif Jasim.

Doctor Haidar Khalifa at Baquba's main hospital said three members of the national guard were killed and six were admitted suffering from burns.

He said rescuers also found the remains of a body on the scene that appeared to be that of the human bomber.

This incident comes less than a week after another bombing outside a rapid reaction police unit in Baquba, northeast of Baghdad, killed 70 people and wounded 56, most of them applicants for jobs in the police.