A suicide car bomb attack in a densely-populated neighbourhood of Baghdad this morning killed at least 32 people and left dozens wounded.

Many of the victims were daily labourers waiting for jobs at an intersection in Sadr City, a sprawling majority Shia neighbourhood in the northeast of the capital that has been repeatedly targeted.

Pictures posted on social media shortly after the explosion showed a huge plume of black smoke billowing into the sky and seriously injured people being evacuated.

According to a police colonel, at least 32 people were killed and 61 wounded in the blast, the second major attack in Baghdad in three days.

At least 27 people were killed by twin explosions in a busy market area in central Baghdad on Saturday, in what was the deadliest such attack in the Iraqi capital in two months.

The so-called Islamic State jihadist group has claimed responsibility for the attack. It also said it was behind the double bombing on New Year's Eve.

The caliphate IS proclaimed in 2014 is shrinking steadily and jihadist fighters are defending Mosul, their last major urban stronghold in Iraq.

Observers have voiced fears that the group, once it definitively loses its status as a land-holding force, could increasingly revert to targeting civilians in Iraq's cities.

IS has also claimed responsibility for an attack on a police station in the city of Samarra in central Iraq.

A group of attackers wearing suicide vests stormed the building in the city, 110 kilometres north of Baghdad.

A spokesperson for the interior ministry said the attackers holed up inside the police station were exchanging fire with the security forces besieging them.

A police major from Salaheddin province where Samarra is located said five attackers had already been killed and added that reinforcements had been deployed.

Meanwhile, French President Francois Hollande has said the battle to retake the Iraqi city of Mosul from IS could be won this spring.

"It was confirmed to us that we could possibly achieve this goal in spring, in any case before summer," Mr Hollande said on a visit to Iraq.