Insurgents have unleashed a string of bomb attacks mainly targeting Shia Muslim pilgrims across Iraq, killing at least 22 people and extending a wave of deadly bloodshed into a second day.
The eruption of violence on Thursday follows nearly two weeks of relative calm, and threatens to inflame rising tensions among Iraq's ethnic and sectarian groups.
The worst attack took place near Dujail, 50 miles north of Baghdad, where a pair of car bombs exploded near pilgrims who were travelling on foot to a shrine in the town of Samarra.
The head of the Salahuddin provincial health directorate, Raed Ibrahim, said 11 people were killed and more than 60 were wounded in that attack.
"We heard thunderous explosions, and everybody went outside and saw burning cars and several bodies on the ground. Market stalls on both sides of the road were on fire," said Naseer Hadi, who works in the Dujail post office.
The pilgrims were heading to Samarra to commemorate the death of two prominent Shia imams who are buried in the al-Askari shrine there.
A 2006 bombing at the gold-domed shrine that was blamed on al-Qaida in Iraq set off years of retaliatory bloodshed between Sunni and Shia extremists that left thousands of Iraqis dead and pushed the country to the brink of civil war.
The attacks in Dujail came hours after a car bomb struck a bus carrying foreign pilgrims near the southern Shia holy city of Kerbala. Four people were killed and 12 were wounded in that attack, according to police and hospital officials.
The explosion tore through the undercarriage and blew out most of the windows of the white and blue tour bus that was hit. Nusaif al-Kitabi, deputy chairman of the Kerbala provincial council, said the bus was carrying pilgrims from Afghanistan.
In the town of Qassim, 78 miles south of Baghdad, a parked car bomb exploded near a bus stop, killing five people and wounding 20. The casualties included Shia pilgrims who were heading to Kerbala, said police and hospital officials.
Shia pilgrims are a favourite target for Sunni insurgents who seek to undermine the country's Shia-led government and provoke a return to sectarian fighting.
In north-eastern Baghdad, a roadside bomb apparently meant to hit an army patrol missed its target and struck a civilian car, killing two passengers and wounding two others, said police and hospital officials.
Thursday's bloodshed comes a day after a wave of attacks killed at least 33 people across Iraq in the country's deadliest day in more than a month.