Baghdad: A bomb hidden on a motorcycle exploded at a secondhand market in Iraq’s capital, the deadliest of a series of bombings on Thursday around Baghdad that killed at least 31 people, authorities said.

The motorcycle market blast struck Baghdad’s sprawling eastern Sadr City district as night fell, killing at least 22 people and wounding 45, officials said. It appeared as though the motorcycle bomb had been slipped in among the other bikes on display, officials said.

Meanwhile, two other bombs struck across the capital targeting minibuses ferrying home labourers at the end of the work day. In Sadr City, officials said a bomb attached to a minibus exploded, killing five civilians and wounding 14. Another bomb stuck on a minibus killed four and wounded 11 in the northern Shaab neighborhood, authorities said.

A police officer and two medical officials confirmed casualty figures for the attacks. They spoke on condition of anonymity as they were not authorised to speak to journalists.

No group immediately claimed responsibility for the attacks, but it bore the hallmarks of insurgents who frequently use car bombs and suicide attacks in their bid to undermine confidence in the Shiite-led government. Such bombings have increased along with Sunni anger over perceived mistreatment and random arrests by the government.

Both Sadr City and Shaab are predominantly Shiite.

Last year, Iraq saw the highest death toll since the worst of the country’s sectarian bloodletting began to subside in 2007, according to United Nations figures. The UN said violence killed 8,868 last year in Iraq.

Fierce clashes pitting government security forces and allied Sunni tribal militias against a coalition of insurgents also have been raging in Iraq’s Anbar province since late December. An Al Qaida offshoot and other insurgent groups have taken control of the city of Fallujah and parts of the provincial capital, Ramadi. Thousands have fled the violence.