“The preliminary examination has found that there is a reasonable basis to believe that various forms of abuse were committed by members of UK armed forces against Iraqi civilians in detention,” it said.
However, the United Kingdom had taken genuine action to investigate the crimes itself, prosecutors found.
In June, British independent investigators looking into allegations of war crimes committed in Iraq told the BBC that of the thousands of complaints they had investigated all but one had been dismissed.
Despite this outcome, which Bensouda said deprived the victims of justice, the ICC prosecutor concluded that British authorities had not been unwilling to carry out investigations or prosecutions and closed the ICC probe.
The ICC has been under fire by Washington for opening a full-fledged investigation into war crimes allegedly committed by US troops on the territory of ICC member Afghanistan. The government of President Donald Trump this year imposed sanctions on Bensouda because of the probe.
Last month, a report by Australian authorities said the country’s special forces allegedly killed 39 unarmed prisoners and civilians in Afghanistan between 2005 and 2016, leading other countries to re-examine the conduct of their troops.