Iraq IS: Scores found dead in mass graves in Anbar
Scores of bodies of Sunni Muslim tribesmen apparently killed by Islamic State (IS) militants have been found in mass graves in western Iraq.
The graves that were found in the province of Anbar may contain between 80 and 220 bodies, reports suggest.
Many of the dead belong to the Al Bu Nimr tribe, which joined Iraq's Shia-dominated government in fighting IS.
It has also emerged that Islamic State may have killed 600 prisoners at a jail in Mosul they seized in June.
The inmates were forced to kneel along the edge of a ravine before being shot, the campaign group Human Rights Watch said.
A graphic video allegedly showing some of the victims of the IS attack in the Anbar town of Hit has emerged online.
Analysis: Orla Guerin, BBC News, Baghdad
Details about the latest mass executions attributed to the self-declared Islamic state are still sketchy, particularly the number of victims.
The bodies - all male - were discovered in two separate locations in Iraq's contested Anbar province.
Footage alleged to be the aftermath of the killings shows a line of blood-soaked bodies dumped in a street. Several are blindfolded, and some have their hands bound.
The video - which cannot be independently verified - shows cars and pedestrians passing by the bodies.
Analysts say mass killings are a very deliberate strategy by Islamic State to spread terror in their opponents.
This latest atrocity is a stark warning to Sunni tribesmen as the Iraqi government and the White House tries to get more of them involved in battling IS.
One local official, Sabah Karhout, described the killings in Anbar province as a crime against humanity and called for more international support for Sunni tribes fighting the militants in Anbar.
US Defence Secretary Chuck Hagel said the killing of Sunni tribesmen in Iraq by Islamic State fighters was the brutal "reality of what we're dealing with" in the conflict.
The US military chief, Gen Martin Dempsey, said American advisers should be sent to Anbar province, but that first Baghdad must arm local Sunni tribes.
"We need to expand the 'train, advise and assist' mission into Anbar province but the precondition for that is that the government of Iraq is willing to arm the tribes," he told reporters on Thursday.
IS militants have killed hundreds of people in the large areas of Iraq and neighbouring Syria they control.