Clashes broke out between peshmerga fighters and the PKK on Friday after one party was deployed to an area controlled by another in northwestern Iraq, two Kurdish security sources said.
The clashes took place in the Sinjar area after Peshmerga Rojava forces were deployed towards the Syrian border on Thursday.
That area is controlled by forces affiliated with the PKK, which is designated as a terrorist organisation by Turkey, the US, and the EU.
"This morning at seven, clashes started with DShK (heavy machine gun). Now there are martyrs [dead] and wounded on both sides," said a Kurdish security source.
The Peshmerga Rojava is made up of Kurds from Syria and was formed and trained in Iraq under the auspices of the Kurdistan Democratic Party (KDP) led by Mesut Barzani, leader of the Kurdistan Regional Government of Iraq, which enjoys good relations with Turkey.
TRT World's Nicole Johnston has more details from Erbil, Iraq.
Threat to Kurdish regional government (KDP)
The PKK established a foothold in Sinjar after aiding Iraq's Yazidi population when Daesh overran the area in the summer of 2014.
Turkish foreign minister, Mevlut Cavusoglu, on Friday said the PKK posed "a threat against the legitimate regional government in Northern Iraq and they are used by some countries against the current administration there."
"It's our duty to destroy these terrorist organisations wherever they are," the minister told reporters in Ankara.
Friday's clash between the two Kurdish groups highlights the risk of conflict and turf wars between the multiple forces arrayed against Daesh, many of which lean on regional patrons for political support or arms.