Another four soldiers were injured when a handmade bomb detonated as an armoured vehicle drove past in the Yuksekova district of Hakkari province, the governorate said in a statement.
It blamed a "separatist terrorist organisation" -- the official term for the outlawed Kurdistan Workers' Party (PKK).
99 Kurdish militants killed in latest operations: Turkish military
The PKK has waged an insurgency in Turkey since 1984, during which over 40,000 people have been killed.
The group is blacklisted as a terrorist organisation by Ankara, the United States and the European Union.
After the collapse of a two-year ceasefire in 2015, Turkish military operations intensified while there are frequent PKK attacks on soldiers in the southeast.
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