Prosecutors have asked the Turkish military to provide images taken by drones during an air strike that killed 35 young Kurdish smugglers on the Iraqi border, the Anatolia news agency said on Saturday.
Turkish fighter jets killed the 35 Kurds during an operation last Wednesday the government admitted was a "blunder" that mistakenly hit civilians instead of Kurdish separatist guerrillas.
Turkey's military command said it had ordered an attack on Kurdistan Workers' Party (PKK) militants after a spy drone spotted a group moving toward its sensitive south-eastern border under cover of darkness.
A large-scale investigation into the incident is under way, said Anatolia, adding that the prosecutor's office in Sirnak province requested that the military send images taken by the unmanned aerial vehicles during the air raid.
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The prosecutor's office will also hear eyewitnesses from the region as part of the investigation, it said.
Clashes between Kurdish rebels and the army have escalated in recent months.
The Turkish military launched an operation on militant bases inside northern Iraq in October after a PKK attack killed 24 soldiers in the border town of Cukurca, the army's biggest loss since 1993.
Hundreds of Kurds demonstrated Saturday in Diyarbakir, the main city of the majority Kurdish southeast, after police said two PKK members had been killed in a shootout.
The PKK took up arms in southeastern Turkey in 1984, sparking a conflict that has claimed about 45,000 lives.