Al-Qaeda front group the Islamic State of Iraq and the Levant on Sunday claimed a wave of attacks that killed 74 people and injured hundreds during the Eid al-Fitr holiday a day earlier.
"The Islamic State mobilised... in Baghdad and the southern states and others to convey a quick message of deterrence on the third day of Eid al-Fitr" in response to security forces' operations, a statement posted on jihadist forums said.
Iraqis have angrily blamed the authorities for failing to prevent a series of deadly bombings and other attacks on Saturday, which came as the country marked the end of the Muslim holy month of Ramadan, its deadliest in years.
The attacks came just weeks after assaults on prisons near Baghdad, also claimed by the Al-Qaeda front group, freed hundreds of prisoners including leading militants, prompting warnings of a surge in violence.
Nine people were killed in fresh violence around the country on Sunday.