The pair, who were killed late Monday, were members of the Sinjar Resistance Units, a group founded among the district's Yazidi community in response to a brutal occupation by jihadists of the Islamic State group nearly a decade ago.

There was no immediate word from the Turkish military, which has conducted a deadly air campaign against PKK targets in Iraq and neighbouring Syria but rarely comments on individual strikes.

"A Turkish army drone targeted a vehicle of the Sinjar Resistance Units in the town of Sinuni, killing a security official and a fighter who was escorting him," the counterterrorism services of Iraq's autonomous Kurdish region said in a statement.

Sinjar and its adjacent mountains are one of the twin heartlands of Iraq's Yazidi community, a non-Muslim Kurdish speaking minority that was savagely oppressed by IS jihadists when they overran the district in 2014.

Hundreds of Yazidi men were executed while women were repeatedly raped and shared out among jihadist fighters as sex slaves in a reign of terror qualified as genocide by UN investigators.

The Sinjar Resistance Units were formed in 2014 with help from fellow Kurds of the PKK, a group blacklisted by Turkey and many of its Western allies as a terrorist organisation.

The Sinjar force is also affiliated to the Hashed al-Shaabi, an alliance of mainly Shiite armed groups formed to fight IS and now integrated in the regular armed forces.

Last month, Turkish President Recep Tayyip Erdogan vowed to continue stepping up its strikes on "terrorist" targets in Iraq and Syria.

Turkey has operated several dozen military posts in northern Iraq for the past quarter of a century in its decades-old war against the PKK.