Iraq has boosted security amid fears of Islamic State group attacks on Shiite pilgrims flocking to the shrine city of Karbala as further reports emerged of mass killings.
The pilgrims are prime targets for the IS jihadists, who have carried out a series of mass executions in recent days, killing scores of members of a tribe in Iraq's western Anbar province.
The jihadists are reported to have slaughtered dozens of members of the Sunni Albu Nimr tribe, which took up arms against them in Anbar.
On Monday, tribal leader Naim al-Kuoud al-Nimrawi told AFP that IS "executed 36 people, including four women and three children" on Sunday alone.
Accounts have varied as to the number and timings of the executions, but sources have spoken of more than 200 people murdered in recent days.
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A police officer and an official gave figures of more than 200 to 258 people killed, while Iraq's human rights ministry put the toll at 322 and a tribal leader said 381 were executed.
The mass killings appear aimed at discouraging resistance from powerful local tribes in Anbar, where IS overran large areas in June as pro-government forces suffered a string of setbacks.
Hundreds of thousands of pilgrims are expected in Karbala for the Tuesday peak of Ashura marking the death of Imam Hussein, one of Shiite Islam's most revered figures.
At least 19 people were killed in bomb blasts targeting Shiites in Baghdad on Sunday, and security forces were on alert for further attacks.
More than 26,000 members of the security forces were deployed in Karbala itself, backed by helicopters providing air support and monitoring desert areas.
A US-led coalition of Western and Arab nations has continued a wave of air strikes on IS positions in Iraq and Syria, with Canadian CF-18s conducting their first raids on Sunday around the Iraqi city of Fallujah.
The Pentagon said its aircraft carried out five strikes on Sunday and Monday around Syria and nine in Iraq.
