The incident took place on Sunday night when IS militants attacked a Hashd Shaabi vehicle near their outposts in Naft Khana area at the edge of the town of Khanaqin, some 160 km northeast of Baghdad, leaving two paramilitary members killed and four others wounded, Abu Sajad al-Shamari, a leading figure of Diyala's provincial Hahsd Shaabi, told Xinhua.

Later on, a reinforcement force from the Hashd Shaabi dispatched to the scene of the blast, but was ambushed by the extremist militants sparking a fierce clash for several hours, leaving at least two Hashd Shaabi members killed and wounding eight others, including the leader of Hashd Shaabi's 20th Brigade, al-Shamari said.

Despite repeated military operations in the Diyala province, remnants of IS militants are still hiding in some rugged areas near the border with Iran, and in the sprawling areas extending from the western part of the province to the Himreen mountainous area in north of the provincial capital Baquba, which itself located some 65 km northeast of the Iraqi capital Baghdad.

The security situation in Iraq has been dramatically improved after Iraqi security forces declared they had fully defeated the extremist IS militants across the country late in 2017.

However, groups of extremist militants melted or regrouped in urban or in deserts and rugged areas, and have been carrying out attacks against the security forces and civilians despite operations from time to time to hunt them down.