The Islamic State group has carried out a fresh wave of mass killings, executing more than 200 members of an Iraqi tribe which took up arms against the jihadists.
Women and children were said to be among scores of Albu Nimr tribespeople executed over the past 10 days in western Iraq's Anbar province.
Reports of the killings came with the country on edge as hundreds of thousands of Shiites prepare to travel to shrine city Karbala this week for a major annual pilgrimage.
IS, a Sunni extremist group that has seized large parts of Iraq and Syria, is expected to target Ashura pilgrims, and 19 people died in attacks on Shiites on Sunday.
The executions in Anbar came after Sunni Albu Nimr tribesmen took up arms against IS in the province, large parts of which have been overrun by the jihadists.
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Accounts varied as to the number and timings of the executions, but all sources spoke of more than 200 people murdered in recent days.
Police Colonel Shaaban al-Obaidi told AFP that more than 200 people were killed, while Faleh al-Essawi, deputy head of Anbar provincial council, put the toll at 258.
The killings are probably aimed at discouraging resistance from powerful local tribes in Anbar.
IS also detained dozens of members of the Jubur tribe in Salaheddin province, north of Baghdad, officials and a tribal leader said.
Jubur tribesmen and security forces have been holding out for months against IS in the provincial town of Dhuluiyah.
Pro-government forces have suffered a string of setbacks in Anbar in recent weeks, prompting warnings that the province, which stretches from the borders with Jordan and Saudi Arabia to the western approach to Baghdad, could fall entirely.
Security forces who wilted before a lightning IS offensive in June are fighting to retake territory seized by the jihadists in Iraq's Sunni Arab heartland.
IS has declared an Islamic "caliphate" in territory it controls, imposing its harsh interpretation of sharia law and committing widespread atrocities.
Like other Sunni extremist groups, IS considers Shiites to be heretics and frequently attacks them, posing a major threat to the Ashura religious commemorations which peak on Tuesday.
Two car bombs targeting Shiites in Baghdad ahead of Ashura killed at least 19 people on Sunday, officials said, while a city centre car bombing near a police checkpoint killed at least five.
