The Turkish armed forces said a military helicopter that crashed during clashes that killed eight soldiers and two pilots last week, may have been brought down by Kurdish fighters with a ground-to-air missile.
If confirmed, it would be the first known usage in recent years of such weaponry by Kurdistan Workers Party (PKK) fighters.
The armed group has been locked in battle with the Turkish army for three decades, aiming for Kurdish autonomy in Turkey's southeast.
The army initially said the helicopter had crashed on Friday due to a technical fault during air operations against PKK fighters in the province of Hakkari near the border with Iraq.
"As the helicopters carried out their mission, the conclusion has been reached that one helicopter may have been struck and downed with an air defence weapon that could have been a missile, possibly fired from the ground," the military said in a statement on Thursday.
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After the collapse of a ceasefire last July, Turkey's southeast has seen some of its worst fighting since the height of the Kurdish uprising in the 1990s.
Thousands of people, including hundreds of civilians, have been killed in the violence since July.
President Recep Tayyip Erdogan, who had spearheaded the peace process between the state and the PKK, has ruled out any return to negotiations and has vowed to crush the armed group.
The PKK is considered a terrorist organisation by Turkey, the European Union and the United States.
Late on Wednesday, US President Barack Obama and the Turkish leader discussed strengthening cooperation in fighting all groups they deemed terrorist organisations, including the PKK, Erdogan's office said in a statement.