Suicide bomber kills 33 anti-ISIS fighters and soldiers south of Baghdad

BAGHDAD (AFP, Reuters) - A suicide bomber attacked Sunni fighters opposed to the Islamic State in Iraq and Syria (ISIS) extremist group as they gathered Wednesday to receive salaries south of Baghdad, killing 33 people and wounding 55 others, Iraqi police and medical officials said.

The bomber blew himself up near the line of the fighters, known as Sahwa, waiting for their salaries in Madaen, about 25 km from Baghdad, the officials said, adding they expected the toll to rise.

The dead were mostly Sahwa fighters, but included at least three soldiers.

"The attacker was wearing an Iraqi army uniform, and an explosive vest packed with ball bearings," a police officer said.

There was no immediate claim of responsibility for the attack, but suicide bombings are a tactic almost exclusively employed by Sunni extremists in Iraq, including ISIS.

ISIS spearheaded a sweeping militant offensive that has overrun much of Iraq's Sunni Arab heartland since June - areas that Shi'ite-led government forces have sought local Sunni help to retake.

The Sahwa, or "Awakening" in Arabic, date back to the height of the US-led war in Iraq, when Sunni tribesmen joined forces with the Americans to battle insurgents including ISIS's predecessor organisation, the Islamic State of Iraq.

The Sahwa were key to sharply reducing violence, but when Iraq's government took over responsibility for their salaries they were sometimes paid late or not at all.

Now Sunni fighters, including the Sahwa and other armed tribesmen, again have an important role to play in the fight against ISIS.

The Iraqi government has distributed arms and ammunition to tribesmen, and Prime Minister Haider al-Abadi aims to establish a national guard made up of local fighters, though the necessary law has yet to pass parliament.

Iraqi security forces backed by US-led air strikes, Kurdish forces, Shiite militias and Sunni tribesmen have clawed back some ground from ISIS.

But major areas, especially north and west of Baghdad, remain outside government control.