BAGHDAD: At least 52 people were killed on Thursday as a motorcycle rigged with explosives detonated in Baghdad's Sadr City and militants targeted mostly Shia neighbourhoods around the country.

The motorcycle was parked in a second-hand bike market in the Shia Muslim neighbourhood that was filled with people, mostly young men, when it exploded late Thursday afternoon,killing 31 and wounding 51 others, Iraqi medical and police sources said.

Blood covered the ground, storefront windows were shattered and shoes and motorcycle parts were strewn around the market,according to a Reuters correspondent at the scene.

Dozens of people were screaming for information about their relatives.

A wounded man, who identified himself as Ahmed, rested in a nearby hospital. “I was about to leave the market when a huge explosion happened,” Ahmed said. “I was hit in my face and my hands and when I got up, everyone was screaming and running towards me away from the blast.”

It was not clear who was behind the bombing but violence against Shias is often blamed on the Sunni Muslim Islamic State of Iraq and the Levant (ISIL), an al Qaeda-linked group.

In other violence the same day, four people died from bombs on two different mini-buses in Shia sections of Baghdad.

A militant smashed his explosives-packed vehicle into a checkpoint, killing three soldiers and wounding six others in Mushaada, a Sunni district, in northern Baghdad, police said.

In Salahuddin province, a pro-government Sunni-manned checkpoint in the town of Shirqat was hit by a bomb that killed two fighters and wounded four others, police said.

A suicide car bomber piled into the greeting house of a prominent tribal leader in Haditha in western Anbar province,killing Sheikh Said Fleah al-Usman and six of his guests and wounding 22 others, police said.

Usman had been a leader of the pro-government “Awakening” paramilitary force and a member of Haditha's municipal council.

The manner of his death reflected the bloody struggles taking place within the Sunni community in Anbar as some support the government, others back al Qaeda linked groups and some factions are opposed to both.

To the north in Tuz Khurmatu, a bomb in an outdoor marketplace frequented by Shia Turkmen killed two people and wounded 11 others.

In Diyala province to the east, which has been roiled by tit-for-tat violence between Sunnis and Shias, gunmen shot dead three members of a Sunni family in Khallis as they drove home, police said.

No reason was given for the killings.