Three car bombs in Baghdad, including a huge blast at a market in a Shiite area, killed at least 86 people today, the bloodiest day in the Iraqi capital this year.

The attacks, the deadliest of which was claimed by the Islamic State group, came with the government locked in a political crisis that some have warned could undermine the fight against the jihadists.

The worst bombing struck the frequently targeted Sadr City area of northern Baghdad at around 10:00 am (local time), killing at least 64 people and wounding 82 others, officials said.

The blast set nearby shops on fire and left debris including the charred, twisted remains of a vehicle in the street. Dozens of angry people gathered at the scene of the bombing, blaming the government for the carnage.

"The state is in a conflict over (government positions) and the people are the victims," said a man named Abu Ali. "The politicians are behind the explosion."

Abu Muntadhar echoed his anger.

"The state is responsible for the bombings that hit civilians," the local resident said. The politicians "should all get out."

Cleric Moqtada al-Sadr, who spearheaded a protest movement demanding a cabinet reshuffle and other reforms, has a huge following in the working class neighbourhood of Sadr City, which was named after his father.

Another suicide car bomb attack killed at least 14 people at the entrance of the northwestern neighbourhood of Kadhimiya, which is home to an important Shiite Muslim shrine.

Access to the neighbourhood, which has also been repeatedly targeted over the years, is heavily controlled. Several members of the security forces were among the victims, hospital sources said.

In the Jamea district in western Baghdad, another car bomb went off in the afternoon, killing at least eight people and wounding 21, an interior ministry official and medics told AFP.

IS issued an online statement claiming responsibility for the attack in Sadr City and saying a suicide bomber it identified as "Abu Sulaiman al-Ansari" detonated the explosives-rigged vehicle.

There was no immediate claim for the two subsequent bombings but all such attacks recently have been perpetrated by IS. The UN's top envoy in Iraq, Jan Kubis, condemned the bloodshed.

IS, which overran large areas in 2014, considers Shiites, who make up the majority of Iraq's population, to be heretics and often targets them with bombings.