Iraqi militias armed so they could help fight the Islamic State group are using those arms to commit atrocities, Amnesty International said Thursday. Above, people look at a burned vehicle at the site of car bomb attack in a busy square at Baghdad's sprawling Sadr City district, Jan. 6, 2017. Ahmed Saad/Reuters

UPDATE: 6:45 p.m. EST — Iraq rejected the report's conclusions, saying the militias do all they can to protect civilians, and urged Amnesty to investigate the "real atrocities.

Original story:

Amnesty International says arms provided to Iraqi militias ostensibly to fight the Islamic State group instead are being used to commit war crimes, revenge attacks and other atrocities.

In a report released Thursday, the human rights group said the arms are coming from Iraqi military stockpiles provided by the United States, Europe, Russia and Iran.

Photographic and video evidence collected since June 2014 shows the predominantly Shiite militias have used the arms, ranging from tanks and artillery to small arms, to abduct thousands of mainly Sunni men and boys, who were tortured and many of whom were killed in extrajudicial executions. The evidence also shows “wanton destruction of property,” Amnesty said.

“International arms suppliers, including the USA, European countries, Russia and Iran, must wake up to the fact that all arms transfers to Iraq carry a real risk of ending up in the hands of militia groups with long histories of human rights violations,” Patrick Wilcken, researcher on arms control and human rights at Amnesty International, said in a statement.

“Any state selling arms to Iraq has to show that there are strict measures in place to make sure the weapons will not be used by paramilitary militias to flagrantly violate rights. If they haven’t done that, no transfer should take place.”

As many as 50 militias are operating in Iraq, known as popular mobilization units. The units generally work with the regular Iraqi army, which turns a blind eye when revenge attacks against Sunnis are mounted, Amnesty said.

“Many Sunnis were grabbed in the streets or dragged from their homes and instantly killed. In the first week of the events, militiamen drove around with speakers shouting for Sunni men to come out of their homes. On 13 January [2016], more than 100 men were taken and have not been seen since,” a witness from Muqdadiya told Amnesty investigators.

A 20-year-old student told investigators that as he fled fighting in Shargat, he was stopped at a checkpoint, blindfolded and driven away. He said he was tortured for the next seven weeks as his tormentors tried to get him to confess to being a member of ISIS.

Amnesty urged Iraq to do a better job of vetting the militias.

“Those suspected of committing serious violations must be removed from their ranks, pending judicial investigations and prosecutions. Unaccountable and unruly militias must be either truly brought into the fold and discipline of the armed forces, or disarmed and demobilized completely,” Wilcken said.

Amnesty said it recognizes Iraq is facing a widespread security threat from ISIS and that the terrorist group is committing atrocities in the areas it controls. But responses must respect international human rights and humanitarian law, the group said.

In the latest incident in Iraq, ISIS killed at least 14 people Thursday in two explosions in Baghdad, Reuters reported.