At least 170 people have been killed in a string of attacks in
In the deadliest incident, some 120 people were killed in a car bombing in a food market in Sadriya district.
A witness said the area had been turned into "a swimming pool of blood".
The attacks came as Prime Minister Nouri Maliki said Iraqi forces would assume control of the country's security by the end of the year.
US Defense Secretary Robert Gates said the attacks were "a horrifying thing," but said insurgents would not derail the ongoing security drive in
'Burned alive'
The bomb in Shia-dominated Sadriya was reportedly left in a parked car and exploded at about 1600 (1200 GMT) in the middle of a crowd of workers and shoppers.
The market was being rebuilt after it was destroyed by a bombing in February which killed more than 130 people.
The powerful bomb started a fire which swept over cars and minibuses parked nearby, burning many people and sending a large plume of smoke over
Television pictures showed a blasted scene littered with blackened and twisted wreckage.
One witness told the Reuters news agency that many of the victims were women and children.
"I saw dozens of dead bodies," the man said. "Some people were burned alive inside minibuses. Nobody could reach them after the explosion.
"There were pieces of flesh all over the place."
Ahmed Hameed, a shopkeeper in the area said: "The street was transformed into a swimming pool of blood."
About an hour earlier, a suicide car bomb attack on a police checkpoint in
Another parked car bomb killed at least 11 people near a hospital in the Karrada district of Baghdad, while in al-Shurja district at least two people were killed by a bomb left on a minibus.
Two other attacks in the capital killed and wounded several more people.
Hospitals in
Car and suicide bombings have occurred almost daily in
The bombers are proving that they can slip through the tightened security net and defy the clampdown, says the BBC's Jim Muir in
Security handover
Most of the attacks have been in Shia areas, increasing pressure for the Shia militias to step up their campaign of reprisal killings against the Sunni community in which the fighters are based, says BBC correspondent.
As
Maysan is the fourth of the country's 18 provinces to be handed over to Iraqi security control.
"Then it will be province by province until we achieve [the complete transfer] before the end of the year," he said in a speech at the handover ceremony delivered on behalf of Prime Minister Maliki.
On Monday, the Iraqi parliament bloc loyal to radical cleric Moqtada Sadr withdrew from the cabinet, demanding Mr Maliki set a timetable for a
But foreign troops are likely to remain in
Analysts say that even if Iraqi forces take the lead in providing security across the country, they will need support from US and other coalition troops.
The attacks in
The UN estimates up to 50,000 people flee the violence in
Photo caption
The Sadriya market was being rebuilt after an earlier attack in February which killed more than 130 people