Twelve prisoners convicted on terror charges in Iraq have been hanged following a recommendation by the premier to speed up the executions.

Haider al-Abadi's office announced on Friday that the convicts were hanged the previous evening after they had exhausted all possibilities for appeal.

The Justice Ministry released a photograph of the execution.

Mr Al-Abadi is facing questions over security in the country after the bodies of eight policemen and members of a pro-government Shiite militia were found on the side of a road north of Baghdad earlier this week.

The eight were believed to have been abducted by Islamic State militants earlier this month.

Mr Al-Abadi on Thursday urged Iraqi President Fuad Masum to immediately sign execution orders for all convicted terror suspects sentenced to death.