A Kurdish Peshmerga fighter with a Milan anti tank weapon guards in a battle with ISIS militants in Iraq, October 24, 2016.

Five Iraqi Kurdish Peshmerga fighters were killed by mistake in a Turkish air raid on a nearby position of the Kurdish Workers Party (PKK) militants on Tuesday in northern Iraq, Kurdish sources said.

The Turkish military carried out air strikes against PKK militants near Iraq’s Sinjar mountains and northeastern Syria to prevent the group from sending weapons and explosives for attacks inside Turkey, it said.

The two regions have become “terror hubs”, the Turkish army said, with the PKK frequently using these areas to channel militants, weapons, bombs and ammunition into Turkey.

“To destroy these terror hubs which threaten the security, unity and integrity of our country and our nation and as part of our rights based on international law, air strikes have been carried out….and terrorist targets have been struck with success,” the Turkish army said in a statement.

The air bombardment was carried out around 02.00 a.m. (2300 GMT) local time, it added.

Designated a terrorist group by Turkey, the United States and the European Union, the PKK has waged a three-decade insurgency against the Turkish state for Kurdish autonomy. More than 40,000 people have been killed in the conflict.

Turkish President Tayyip Erdogan has for months said the PKK has taken a foothold in Sinjar region in Iraq’s northwest, around 115 km (71 miles) from the Turkish border, and that Ankara would not allow the group to expand its activities there.

In November, the Turkish army deployed tanks and armoured vehicles to the border town of Silopi, around the time Iraqi forces supported by the United States launched an operation to drive ISIS from the northern Iraqi city of Mosul.

The government at the time said the move was to fortify Turkey’s defenses against developments across its borders.

Turkish President Tayyip Erdogan speaks in a news conference in Turkey April 16, 2017.