RNA - 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, AFP reported.
Hundreds of thousands of pilgrims from Iraq and abroad are heading to Karbala for the Tuesday peak of Ashura, which marks the death of Imam Hussein, one of the most revered figures in Shiite Islam.
At least 19 people were killed in bomb blasts targeting Shiites in Baghdad on Sunday and Iraqi security forces were on alert for further attacks.
Pilgrims have been targeted during Ashura before, but this year's commemorations face even greater danger after IS seized control of large areas of Iraq in a June offensive. Like other terrorist extremists, IS considers Shiites heretics.
Authorities have deployed thousands of security personnel and allied militiamen to protect the pilgrims, in what will be a major test for the new government headed by Prime Minister Haidar al-Abadi.
"The security plan is fully in effect and the security forces are on a state of high alert," an Iraqi police colonel told AFP, speaking on condition of anonymity.
Police were deployed throughout Shiite neighbourhoods of Baghdad and security forces are guarding the 100-kilometre (60-mile) route from the capital to Karbala.
In Karbala, more than 26,000 members of the security forces were deployed, backed up by helicopters providing air support and monitoring desert areas, army Staff Lieutenant General Othman al-Ghanimi told reporters.
At the entrance to the city, police were using X-ray trucks to scan vehicles and sniffer dogs were checking arrivals. Some 1,500 policewomen were also deployed to check female pilgrims.
The Sunni extremist IS group has declared a "caliphate" in parts of Iraq and neighbouring Syria under its control, imposing its harsh interpretation of Islamic law and committing widespread atrocities.
- Mass killings of anti-IS tribe -
In recent days the group is reported to have slaughtered dozens of people from the Sunni Albu Nimr tribe, which had taken up arms against the jihadists in Anbar.
Accounts varied as to the number and timings of the executions, but all sources spoke of more than 200 people murdered in recent days. Women and children were reported to be among the dead.
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 killings are likely aimed at discouraging resistance from powerful local tribes in Anbar, where large areas have been overrun by IS as pro-government forces suffered a string of setbacks.
There are fears the province, which stretches from the borders with Jordan and Saudi Arabia to the western approach to Baghdad, could fall entirely to the jihadists.
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