The tribal fighters first were attacked by small arms fire before a suicide bomber blew up his explosive vest near a group of the fighters, the source said.

The gunfire and the blast killed two tribal fighters and wounded five others, including the leader of the paramilitary group, the source added.

During the past few months, dozens of IS militants fled their former bases in Salahudin province and Hawijah area in the west of Kirkuk after the Iraqi forces cleared these areas during major anti-IS offensives.

However, remnants of IS militants resorted to hideouts near the rivers of Tigris and Zab, as well as Himreen mountainous areas to continue their almost daily attacks against civilians and Iraqi forces in nearby towns and villages.

On Dec. 9, 2017, Iraqi Prime Minister Haider al-Abadi officially declared full liberation of Iraq from IS militants after Iraqi forces recaptured all the areas once seized by the extremist group.

Nevertheless, small groups and individuals of IS militants are still capable of carrying out attacks from time to time.