A suicide bomber detonated a pick-up truck on Wednesday in Sadr City , a heavily populated poor Shi'ite suburb of Baghdad , killing at least 15 and wounding 50, security sources said.

The explosion, the deadliest in Baghdad so far this year, targeted a crowded street full of garages and used car dealers.

Militants have stepped up bombings in Iraq last year, in retaliation to a US-backed campaign that dislodged the hardline Sunni group from most Iraqi cities it took over in 2014. The militants also control parts of neighboring Syria.

This is a developing story.