Two female suicide bombers blew themselves up near the gates of a Shi'ite Muslim shrine in Baghdad on Friday killing 60 people.
At least 125 people were wounded in the blasts that took place within minutes of one another at the Imam Moussa al-Kadhim shrine in the Shi'ite neighbourhood of Kadhimiya, police said.
Many of the dead and wounded were Iranian Shi'ite pilgrims.
The attack was the deadliest single incident in Iraq since 63 people died in a truck bomb blast in Baghdad in June last year.
Police said the attackers approached two gates to the shrine, which contains the tombs of two imams, or holy men, and has been a frequent target of Sunni Islamist extremists who consider Shi'ite Muslims to be heretics.
An interior ministry official said the attackers placed two leather bags full of explosives among the crowds at the two main gates.
They were detonated by grenades whose pull rings were attached to strings and yanked from a short distance away.
The blasts on the Muslim holy day followed two suicide bombs on Thursday, one in Baghdad and the other in the northeastern province of Diyala, in which a total of at least 89 people died.
The latest attacks coincide with growing fears of a resurgence in violence as US combat troops prepare to pull out of Iraqi cities in June, ahead of a full withdrawal by the end of 2011, and amid doubts over the effectiveness of Iraqi forces.