The roadside blast happened in the Sadr city area and targeted an Iraqi army checkpoint. The car bomb exploded in the Hurriya district and appeared to be aimed at a passing police patrol.

Six members of the security forces were among the wounded, police sources said.

Last week at least 36 people were killed and almost 150 wounded by more than 20 bombings that were claimed by Al-Qaeda’s affiliate in the country.

Heightened tension between Shiites, Sunnis and Kurds in the coalition government since US troops withdrew in December has raised fears of a return to sectarian violence of the kind that pushed Iraq to the brink of civil war a few years ago.

The country is less violent than at the height of that conflict in 2006-07, but bombings and killings still happen daily, often aimed at Shiite areas and local security forces.