A series of bomb attacks in the Basra area of southern Iraq has killed at least 68 people and injured many more.
The rush-hour explosions caused panic across Basra
The first blasts - apparently suicide bombings - occurred outside three police stations in Basra city centre during Wednesday's morning rush hour.
Many of the dead and injured were children travelling in passing buses on their way to school.
A fourth attack south of Basra is said to have killed three Iraqis and wounded five UK soldiers.
Elsewhere in Iraq, the restive central city of Falluja has seen fresh clashes between insurgents and US troops.
Meanwhile, the Danish foreign ministry says a Danish man kidnapped in Iraq last week has been found dead.
Most of the victims in Basra died in what the mayor of the city described as suicide car bombings.
Two police stations in the Ashar district and one in the Old City were hit in near-simultaneous attacks.
A wounded Iraqi told Reuters news agency that he heard a huge explosion as he stood at the door of his house.
"I looked around and saw my neighbour lying dead on the floor, torn apart," he said.
"I saw a minibus full of children on fire - 15 of the 18 passengers were killed and three badly wounded."
At least 100 people are thought to have been wounded in the attacks targeting the British-controlled city.
UK soldiers who tried to assist casualties were stoned by protesters who blamed the British for failing to provide security.
Distraught Iraqis stoned coalition forces trying to help
British officials do not think local Shias were responsible for the explosions, but blame them on "al-Qaeda type elements or former regime loyalists".
Briefing reporters in London, one official said: "The Shias have broadly accepted the British presence in Basra and I do not think this has changed."
Shortly after the Basra bombings, two car bombs hit a police academy in the town of Zubair, about 25km (16 miles) to the south.
That attack killed three Iraqis and wounded five British soldiers - one of them seriously - a UK official said.
The BBC's Dominic Hughes in Iraq says that although Iraqi police have been targeted by insurgents in the past, Basra had so far escaped major unrest.
UK Foreign Secretary Jack Straw told reporters in London the insurgents would be defeated and that the transfer of power to Iraqis, scheduled for June, would not be affected.
Iraqi Interior Minister Samir al-Sumeidi said the attacks bore the "fingerprints" of those who carried out the bombings in Irbil and Karbala - in which hundreds died in February and March.
US officials have blamed al-Qaeda-linked groups for these and other bombings in Iraq.
Meanwhile, Italian Prime Minister Silvio Berlusconi has said Italian troops will stay on after the Iraqi handover, to help improve security.
Spain, the Dominican Republic, and Honduras have said they will withdraw their troops from the country.
In Falluja, a city west of Baghdad held by Sunni militants, about 40 fighters attacked besieging US troops early on Wednesday.
The gunmen struck in the north of the city, mounting a barrage of rocket-propelled grenades and small-arms fire.
Explosions could be heard throughout Falluja as marines were put on high alert.
US Defence Secretary Donald Rumsfeld warned on Tuesday that coalition troops would not wait indefinitely for gunmen to surrender in Falluja.
He suggested the chance of a peaceful outcome was remote as militants were not involved in the negotiations.
Ashar: two police stations bombed
Old City: one police station hit
Zubair: police academy attacked