Navi Pillay, UN High Commissioner for Human R
Navi Pillay, UN High Commissioner for Human RReuters

The United Nations’ human rights chief, Navi Pillay, said on Monday that terrorists from the Islamic State of Iraq and the Levant (ISIS) have almost certainly committed war crimes by executing hundreds of non-combatant men in Iraq.

In a statement quoted by Reuters, Pillay said that corroborated reports showed that soldiers, military conscripts, police and others who had surrendered or been captured had been summarily executed in the past five days.

"Although the numbers cannot be verified yet, this apparently systematic series of cold-blooded executions, mostly conducted in various locations in the Tikrit area, almost certainly amounts to war crimes," she said, according to Reuters.

The Islamist terrorists have also executed 13 imams in Mosul for refusing to pledge allegiance to ISIS, according to Pillay, who added, "The provocative language used by ISIL, which has been talking about 'liquidating herds of sheep' and inciting sectarian tensions is clearly intended to sow further chaos and bloodshed in the country.”

ISIS has already captured the city of Mosul and has started to head towards the capital Baghdad.

Earlier on Monday, Pillay told reporters that the situation called for "comprehensive action."

"We want to alert the world to address this immediately," she was quoted by Reuters as having said.

Asked if she wanted the situation in Iraq to be referred to the International Criminal Court, she declined to comment and said she first wanted to establish the facts.

But she also suggested the Iraqi government may have contributed to the sudden advances made by ISIS, which seeks a caliphate ruled on strict Sunni Muslim precepts in Iraq and Syria.

"I've pointed to many times and condemned the shocking number of executions that the Iraqi government is carrying out," Pillay said, adding she wanted to investigated who was being executed and what grievances the killings caused.