At least 18 persons were killed and 20 wounded in two suicide car bombings that targeted the Iraqi police in Baghdad, an official said on Saturday.The attacks occurred on Friday night when a suicide bomber rammed his explosive-laden car into a police checkpoint and detonated it in the Shia neighbourhood of Abu Dsheer, Xinhua news agency reported.Meanwhile, another suicide bomber blew up his car packed with explosives at the entrance of a police station at the vicinity of the first blast, causing heavy damage to the building.An Interior Ministry official said the toll was expected to further rise as many of the injured were in critical condition.The attacks followed another assault near the country's oil hub city of Basra, which hit security checkpoints on a road leading to the oilfield of Rumaila, leaving 13 people dead and 30 injured.No group has so far claimed responsibility for the attacks but the Islamic State group in most cases is responsible for such assaults targeting the security forces and crowded areas across Iraq.The attacks came as Iraqi forces backed by anti-IS international coalition are carrying out a major offensive to drive out the IS from their major stronghold in Mosul.