Twenty-five people have been killed and about 52 wounded in suicide attacks against pilgrims in the Iraqi capital, Baghdad, police say.
The three attacks, carried out by women, targeted Shia pilgrims heading for the Kadhimiya shrine in the north of the city for annual ceremonies.
The bombers struck as pilgrim convoys passed through the Karrada district.
Meanwhile, a suicide attack in the northern city of Kirkuk has killed at least 11 people, officials say.
At least 50 people were injured in the blast, which happened during a Kurdish political demonstration against a new provincial election law.
Tensions have been high in Kirkuk which is disputed between Kurds, Arabs and Turkomans.
Sectarian violence
Baghdad has been under heavy security because of the Shia pilgrimage.
Among those killed in the attacks on pilgrims were women and children, security and hospital officials told AFP news agency.
The BBC's Jim Muir in Baghdad says that major gatherings for Shia religious ceremonies have frequently been the target for bomb attacks.
Such attacks were a feature of the cycle of sectarian violence that gripped Iraq last year.
The Iraqi military spokesman in Baghdad, Brig Gen Qassim al-Moussawi, told AP news agency that 100,000 Iraqi security forces were being deployed - along with US reinforcements and air support - to protect the ceremonies in Kadhimiya.
Security forces are using about 200 women volunteers to search female pilgrims, AP said.
Despite the extra security, gunmen also shot dead seven pilgrims in the southern outskirts of Baghdad on Sunday.
Some Shia pilgrims said they were determined to continue with the ceremonies.
In 2005 more than 900 people died in a stampede on the route to the shrine. The panic had been started by rumors of a suicide bomber in the crowd.
PHOTO CAPTION
Iraqi security officers examine a car damaged by a roadside bomb in Basra, 550 kilometers (340 miles) southeast of Baghdad, Iraq, Sunday, July 27, 2008.
BBC