& 23 February 2012& Last updated at 17:10 GMT &

At least 55 people have been killed and hundreds injured in a wave of bombings and shootings across Iraq, police say.

The violence targeted predominantly Shia areas, in particular police officers and checkpoints.

Dozens were killed in Baghdad, with attacks targeting commuters and crowds. One car bomb in the upmarket Karrada district killed nine people.

No group has yet said it was behind the violence. Attacks in Iraq have risen since US troops withdrew in December.

Tolls from other attacks around Baghdad include:

• Six dead after a car bomb in Shia-dominated Kadhimiya, north of Baghdad
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• Six killed by gunmen at a police checkpoint in the Sarafiya district of the capital
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• Two dead and five injured in an explosion in the western al-Mansour district
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• Two killed and 10 injured in two explosions in Dorat Abo Sheer, southern Baghdad
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• Two killed and nine wounded in an attack by gunmen using weapons with silencers, targeting a police patrol in Saidiya, southern Baghdad
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• Seven injured, most of them policemen, in a blast in al-Madaen, south of Baghdad
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• Five civilians injured in a bomb explosion in Taji, north of Baghdad
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There were also attacks in Mosul, Kirkuk and the province of Salahuddin.

A policeman who survived the Kadhimiya attack described how the car bomb tore through a cafe.

"We were sitting at a restaurant having soup for breakfast when the bomb exploded. I lost consciousness and then saw smoke and dust when I came to," Ahmed Kadhim, who suffered shrapnel wounds, told Reuters.

"I saw people and body parts everywhere."

Eighteen others were injured in the attack.

In the town of Musayyib, south of the capital, a car bomb exploded near a primary school, injuring at least 62 people, many of them children. One person was killed.

Curfews in place

A curfew is now in effect in Tikrit, the capital of Salahuddin, and in Hilla, in Babil province, south of Baghdad.

Last week, at least 18 people were killed in a suicide attack near the Iraqi police academy in the capital.

Shia targets have come under increasing attack since the government of Shia Prime Minister Nouri al-Maliki moved against senior members of the predominantly Sunni Iraqiya political bloc.

The day after US troops withdrew, a warrant was issued for the arrest of Vice-President Tariq al-Hashemi, who is accused of financing death squads.

Mr Hashemi, who denies the charges, is currently in Iraqi Kurdistan, under the protection of the regional government. He is the most senior Sunni politician in the Iraqi government.

The BBC's Rafid Jabbouri, in Baghdad, says Shia government officials accuse people linked to Mr Hashemi of being behind recent outbreaks of violence.

Mr Hashemi has denied any involvement.

Al-Qaeda in Iraq said it carried out previous waves of attacks in December and January.

The blasts come just weeks before Baghdad plans to host an Arab League summit, which has already been postponed.

Parliamentary speaker Osama al-Nujaifi said the attacks aimed to "spark sectarian strife among the Iraqi people and to prevent the Arab League meeting from being held".