Iraqi security services said they believed Al-Qaeda was plotting an attack against worshippers during the Shia Ashura mourning ritual which this year also falls on Tuesday.
"We have deployed 18,000 policemen and soldiers to safeguard the Ashura in Diyala alone," police chief Raid Atiya said.
"We fear Al-Qaeda may launch suicide attacks against Shia worshippers," Atiya said.
Flyers were reportedly distributed in Diyala's capital, Baquba in recent days, containing threats against Shias and vowing that attacks would be carried out during the Ashura.
Ashura is one of the holiest days for Shia Muslims, a day of mourning that honours the martyr Imam Hussein, grandson of the Prophet Mohammed, at the Battle of Karbala in 680 AD.
Sunni extremists have targeted Ashura pilgrims in Iraq and elsewhere in the past. A suspected female suicide bomber was arrested on 7 January 2009 in th northern Iraqi city of Balad Ruz as millions of Shia Muslims gathered across the country for the annual Ashura ceremony.
End item/ 159
