Bombings in Shiite areas of Iraq kill 37

At least 37 people have been killed in the latest series of bombings in Iraq, including 15 in a suicide attack in Sadr City where local Shiite leaders met.

At least 37 people have been killed in the latest series of bombings in Shi'ite areas across Iraq. (AAP)

Bombings that include a suicide attack on tribal leaders in Baghdad have hit Shi'ite areas of central and southern Iraq, killing at least 37 people.

They targeted three Baghdad neighbourhoods as well as Karbala and Basra provinces, south of the capital, officials said.

In the Sadr City area of northern Baghdad, at least 15 people died and 34 were hurt when a suicide bomber detonated explosives inside a tent where local Shi'ite tribal leaders were meeting.

A car bomb struck another northern area of Baghdad, killing 13 people and wounding at least 24, while a roadside bomb in the capital's east killed two people and wounded three.

North of Karbala city, a car bomb killed four people and wounded 13, while another one hit a market west of the southern port city of Basra, leaving at least three dead and seven wounded.

The violence came during a major offensive by Sunni jihadists that overran the entire province of Nineveh and swathes of Kirkuk to its southeast, and Salaheddin to its south.

The drive reached as far as the outskirts of Samarra, just 110 kilometres north of Baghdad, where clashes between security forces and militants ended without them entering the city.

Violence is running at its highest level since 2006-2007, the height of a brutal Sunni-Shi'ite sectarian war in which tens of thousands of people were killed.