An Al-Qaeda-linked group on Sunday claimed a dozen car bombings in Shiite neighbourhoods in Baghdad which killed 50 people last week, part of a nationwide surge in unrest.
The bloodshed was a response to "army and police security campaigns that target Sunni areas," according to a statement posted on a jihadi forum and attributed to the Islamic State of Iraq and the Levant, an Al-Qaeda front group.
Sunni militants linked to the group frequently attack members of Iraq's Shiite Muslim majority, whom they regard as apostates.
The blasts also wounded more than 100 people in the capital, security and medical officials said. Several other attacks in Baghdad and elsewhere the same day killed 11 others.
The bloodshed added to concerns that Iraq is edging towards a return to the sectarian war that killed tens of thousands in 2006-2007, amid a long-running political deadlock and concerns of a spillover from the conflict in neighbouring Syria.
Authorities have responded with wide-ranging security operations targeting militants, but diplomats and analysts say these do not address the root causes of the violence.