At least four people have been killed and 17 others wounded in a car bomb attack in the Sadr City neighbourhood of the Iraqi capital Baghdad, police and medical sources said on Thursday.

The car was parked at a busy second-hand equipment market in the mainly Shia district, police said.

The cause of the blast was not immediately known.

The development comes hours after drone strikes targeted US-led coalition troops near Erbil airport and a Turkish military base in northern Iraq.