A wave of attacks blamed on Al-Qaeda killed at least 42 people on Thursday, in what Iraq's parliament speaker said was an attempt to derail an Arab League summit planned for the end of March.

Security officials and medics said more than 250 people were wounded in the attacks, which hit six different provinces and came just days after a suicide blast near a Baghdad police academy.

"The terrorist Al-Qaeda organisation is trying to send messages to its supporters that it is still operating on Iraqi soil, and that it has the capability to strike in the capital and the cities and both big and small regions," said a statement on the interior ministry website.

Attacks occurred in religiously mixed Baghdad in central Iraq and Babil to its south, and in Sunni-majority Diyala, Salaheddin, and Nineveh provinces north of the capital.

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

At least 16 car bombs and eight roadside bombs exploded, in addition to several shootings and a mortar attack.

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

Parliament speaker Osama al-Nujaifi said the attacks aimed to derail the Arab League summit in Baghdad at the end of March and a planned national conference aimed at political reconciliation.

The attacks "aim to stoke the fires of strife among the sons of the Iraqi people, and to make the holding of the Arab summit and the national meeting fail, and give a clear sign of the involvement of foreign parties trying to export their internal problems to Iraq," Nujaifi said in a statement.

Baghdad bore the brunt of the violence.

A car bomb in the northern Shiite shrine district of Kadhimiyah killed six people and wounded 15, an interior ministry official said, while gunmen attacked a police checkpoint across the Tigris River in Adhamiyah, killing six and wounding three.

Another car bomb exploded in the central Karrada district near a police checkpoint, killing one person and wounding 11, followed by another that killed one and wounded six.

Two roadside bombs and an attack by gunmen on a police checkpoint killed two people and wounded nine in the southwest of the city.

Other attacks in south Baghdad killed four and wounded 20, and a car bomb in Mansur in the capital's west killed two and wounded five.

North of Baghdad, a roadside bomb wounded five people in Taji.

Dr Hassan Ibrahim of the Diyala health directorate said eight people were killed and 24 others wounded in attacks in the province.

A police major in Diyala had earlier said that attacks there included two car bombs, a roadside bomb, and a shooting.

Raed al-Juburi, health chief in Salaheddin province, said eight people were killed and 56 wounded in attacks, including in a key refinery town.

In Babil, a car bomb killed one person and wounded five in provincial capital Hilla, police said.

Another car bomb exploded near a restaurant in Al-Mussayeb, killing a girl of around 10 and another civilian, and wounding 85 other people, most of them primary school pupils, a hospital official said.

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

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

In Mosul, capital of northern Nineveh province, a mortar attack killed one man, police First Lieutenant Mohammed al-Juburi said.

And two car bombs in Nineveh targeted Asiacell mobile provider towers but did not cause any casualties, another police officer said.

The US embassy said in a statement that it "strongly condemns the terrorist attacks that targeted innocent men, women, and children across Baghdad, as well as in Tikrit, Babil, Baquba, and Kirkuk."

"These terrorist acts were targeted at all the people of Iraq in a desperate effort to undermine Iraqi society and its institutions," it said.

UN envoy Martin Kobler also condemned the attacks, saying in a statement: "The continuing violent attacks on Iraqis are totally unacceptable and have to stop."