A wave of bombings and shootings killed at least 38 people and wounded more than 250 on Thursday, Iraq's deadliest day in more than a month, security and medical officials said.

The violence hit five provinces -- religiously mixed Baghdad in central Iraq and Babil to its south, and Sunni-majority Diyala and Salaheddin to its north.

Attacks also hit Kirkuk, an oil-rich province that the autonomous Kurdistan region wants to incorporate against Baghdad's wishes.

It was the deadliest day in Iraq since January 14, when 53 people were killed in a suicide bombing on the outskirts of the southern port city of Basra.

Most of the violence was centred on Baghdad, where attacks killed 22 people, an interior ministry official said.

A car bomb in the Shiite shrine district of Kadhmiyah in north Baghdad killed six people and wounded 15, the official said.

In Adhamiyah, across the Tigris river, gunmen attacked a police checkpoint, killing six people and wounding three.

A car bomb exploded in the Karrada district of central Baghdad near a police checkpoint, killing one person and wounding 11, while another car bomb exploded in the same area about 30 minutes later, killing another person and wounding six.

And two roadside bombs and an attack by unknown gunmen against a police checkpoint killed two people and wounded nine in Umm al-Mualaf in southwest Baghdad.

And in Dura in south Baghdad, a roadside bomb killed two people and wounded 10.

Two roadside bombs exploded near a restaurant in Abu Shir, also in south Baghdad, killing two people and wounding 10.

A car bomb in Mansur in west Baghdad killed two people and wounded five.

And a roadside bomb wounded five people in Taji to the north of Baghdad.

In Diyala province, north of the capital, two car bombs exploded in the provincial capital Baquba, killing three people and wounding eight, while a roadside bomb killed one person, a police major said.

Gunmen also attacked a house west of Baquba, killing two people and wounding a third, while a roadside bomb east of the city wounded a man and his wife.

Raed al-Juburi, the head of the Salaheddin province health directorate, said that eight people were killed and 56 wounded in attacks in the province.

One person was killed and 12 wounded in the refinery town of Baiji, two were killed and eight wounded in Tuz Khormatu, two were killed and three wounded in Suleiman Bek near the border with Kirkuk, one was killed and seven wounded in Dujail, and four killed and 26 wounded in Balad.

In Babil province, south of Baghdad, a car bomb exploded in the provincial capital Hilla at about 8:15 am (0515 GMT) killing one person and wounding five, a police first lieutenant said.

Also south of the capital, a car bomb exploded in Al-Mussayeb, the police officer said. It killed a school girl and wounded 85 other people, most of them fellow pupils, a hospital official said.

A roadside bomb in Al-Nil, north of Hilla, wounded seven people, including three police, the police officer added.

Two car bombs targeting police in the northern oil hub of Kirkuk wounded 25 people, security and medical sources said.