At least 60 people were killed when two suicide bombers blew themselves up within seconds of each other at the gates of a Shia Muslim shrine in Baghdad.
Yesterday's attacks, believed to have been carried out by women, came a day after Iraq was rocked by its most deadly violence in more than a year. On Wednesday, two suicide bombings in separate areas of Iraq killed more than 80 people.
Iraqi police said 25 of those killed in the latest atrocity at the Imam Moussa al-Kadhim shrine in the Shia neighbourhood of Kadhimiya were Iranians. A further 125 people were reported to have been wounded.
No one claimed responsibility but such attacks are the trademark of Sunni insurgents backed by al-Qaida.
Apolice official said the bombers struck shortly before the start of Friday prayers as worshippers streamed into the mosque, which is an important site for Shia pilgrims.
The Prime Minister, Nouri al-Maliki, ordered a military task force to investigate the bombings and relieved the battalion responsible for security in the area of its duties pending the enquiry. The men were suspended for failing to provide adequate protection around the shrine. The site has been a favourite target of insurgents, most recently in early April when a bomb left in a plastic bag nearby killed seven people and wounded 23.
Meanwhile, funerals began yesterday for the 88 people killed in Thursday's bombings in Baghdad and in Baquba. Coffins were loaded on to trucks near the Baghdad office of the Iraqi Red Crescent, whose staff were distributing food parcels in the city centre when a suicide bomber killed 31 and wounded at least 50 others.
Police claim to have arrested Abu Omar al-Baghdadi, who is believed to lead al-Qa'ida in Iraq and the Islamic State of Iraq, a network of Sunni militant groups.