The US on Sunday condemned the killing of 13 kidnapped Turkish citizens in northern Iraq, after Turkish officials said they had been executed by militants from the outlawed Kurdistan Workers Party.
Among those executed were military and police personnel. According to reports, they were killed in a cave in Gara region.
The executions took place during a Turkish military operation launched on February 10 against the PKK, in which 48 militants were killed, according to Turkey's Defence Minister Hulusi Akar.
Twelve of those executed had been shot in the head, and one in the shoulder, he said.
“The United States deplores the death of Turkish citizens in the Kurdistan Region of Iraq,” US State Department spokesman Ned Price said in a statement.
If reports that the PKK was responsible were confirmed, Mr Price said, "we condemn this action in the strongest possible terms".
Turkey launched the military operation against the PKK in Gara region, 35 kilometres south of the Turkish border, to secure its frontier and find citizens who had been kidnapped previously, Mr Akar said.
The governor of Malatya province in southeast Turkey named six soldiers and two police officers, kidnapped in incidents in 2015 and 2016, as being among those killed in the cave.
Three of the dead have yet to be identified in autopsies being carried out in Malatya.
One senior security source said that Turkish intelligence personnel were among the dead.
"According to initial information given by two terrorists captured alive, our citizens were martyred at the start of the operation by the terrorist responsible for the cave," Mr Akar said.
A statement on a PKK website said some prisoners it was holding, including Turkish intelligence, police and military personnel, had died during clashes in the area. The group denied it ever hurt prisoners.
The PKK is a designated a terrorist group by Turkey, the US and EU.
In the last two years, Turkey's fight against the PKK has increasingly focused on northern Iraq, where the group has its stronghold in the Qandil mountains on the Iranian border.