More than 50 people have been killed in a string of suicide car bomb attacks in Iraq's capital, Baghdad, and the southern province of Basra, police have told Al Jazeera.

At least 33 people were killed on Friday in two separate blasts at checkpoints on a highway near oilfields in Basra, according to police.

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The first explosion took place at the Rumeila checkpoint, and the second about one kilometre away at another checkpoint called al-Sadra.

Iraq's South Oil Company said there was no disruption to operations but oil police were put on maximum alert in response to the attack, officials told the Reuters news agency.

Baghdad attacks

Separately, two more attacks late on Friday killed at least 19 people, including security forces, and wounded 25 others in southern Baghdad.

Police sources said a suicide car bomber detonated explosives at the entrance of a checkpoint, just as another attacker blew himself up near a police station located about 100 metres away. 

The Islamic State of Iraq and the Levant (ISIL, also known as ISIS) armed group claimed responsibility for the Baghdad attacks.

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ISIL is under assault in both Iraq - in the country's second city of Mosul - and in neighbouring Syria.

The armed group took vast swaths of Iraqi territory north and west of Baghdad in 2014.

Iraqi government forces backed by a US-led international coalition have since retaken many cities, including Tikrit and Fallujah.

But as ISIL has lost ground in Iraq, it has also retained the ability to stage regular attacks in areas it does not control.

Source: Al Jazeera and news agencies