A group of four terrorists including Mazlum Dağ, the assailant implicated in the killing of Turkish diplomat Osman Köse in Irbil, has been captured alive and detained in northern Iraq a statement from the Irbil Security Directorate said Saturday.

The arrest by Kurdistan Regional Government's (KRG) internal security service Asayish reportedly took place on the road between Irbil and Makhmour, which hosts a refugee camp where the PKK has a significant presence.

"The Kurdistan Region announced on Saturday the arrest of the man who planned the assassination of a Turkish diplomat in a restaurant in Erbil, less than a week after the attack," the Asayish said in a statement.

According to Turkish security sources, the 27-year-old terrorist is one of the perpetrators of Wednesday's attack in which Köse, who was temporarily stationed in Turkey's consulate general in Irbil, was killed by gunshots while eating at a restaurant.

Two Iraqi citizens were also killed in the attack that took place in one of the safest areas in the seat of KRG.

Dağ was identified as one of 13 siblings of the pro-PKK People's Democratic Party (HDP) Diyarbakır Deputy Dersim Dağ, who has two other brothers linked to the terrorist group.

He joined the terrorist group in February 2015 after crossing the Turkish-Iraqi border from the Habur crossing in southeastern Turkey's Şırnak province, reports said.