Local officials said an assailant had driven an explosives-laden vehicle into the checkpoint in the town of Qa'im near the Syrian border on Wednesday.
Police Captain Mahmud Jassem told AFP that 11 people, five of them security personnel, had been killed and 16 others sustained injuries in the incident, Presstv Reported.
The checkpoint was jointly manned by the Iraqi army soldiers and pro-government fighters.
Both Iraqi fighters and civilians have been among the casualties.
The death toll is expected to climb because some of those injured are in a critical condition.
No group has claimed responsibility for the attack yet, but it bears the hallmark of Daesh.
The Takfiri terrorist group unleashed a campaign of death and destruction in Iraq in 2014, overrunning vast swathes in lightning attacks. Iraqi army soldiers and allied fighters then launched operations to eliminate Daesh and retake the lost territory.
Last December, Prime Minister Haider al-Abadi declared the end of the anti-Daesh campaign in the Arab country. The group’s remnants, though, keep staging sporadic attacks across Iraq.