The federal government in Baghdad has often blamed the PKK for carrying out attacks against Turkish targets from its rear bases in Iraq's northern mountains but a statement issued late Friday was a rare accusation against their fellow Kurds by the autonomous regional authorities.

The PKK's armed wing had denied responsibility for the assassination.

But the Iraqi Kurdish authorities said that based on a detailed confession by the suspected Turkish Kurdish gunman, Mazloum Dag, 27, the murder was carried out on the orders of top PKK commanders.

Turkish Vice-Consul Osman Kose was gunned down with two Iraqis while they dined on a restaurant terrace in Arbil.

Iraqi Kurdish security services said that the murder had been three months in the planning by PKK commanders in their heavily forrtified hideouts in Iraq's Qandil mountains.

They said they had arrested three Turkish and three Iraqi suspects.

Dag's arrest last Saturday was immediately seized on by the Turkish media as his sister Dersim is a member of parliament for Turkey's main pro-Kurdish party, the People's Democratic Party (HDP).

The HDP, the country's second largest opposition group, is regularly accused by President Recep Tayyip Erdogan of links to the outlawed PKK.

The HDP "strongly" condemned the Arbil attack, calling it an "absolutely unacceptable provocation attempt".

In May, Turkey launched a major ground offensive and bombing campaign against the PKK in Qandil, the latest of many in the military's three and a half decade campaign against the rebels.

Analysts have suggested the attack on the Turkish diplomat might have been carried out in retaliation for the killing of several PKK commanders in the latest bombing campaign.

Following Kose's murder, Turkey broadened its cross-border operations, launching air strikes against PKK bases and members in the Kurdish-held Makhmur area south of Iraq's second city Mosul.