The eight, who have claimed asylum in Greece, arrived by military helicopter today after sending a distress signal to authorities at the airport in northern Alexandroupolis.
Seven of those on board were in military uniform, ERT TV said.
"They were in Istanbul with the order to transport the wounded. They didn't know what was happening exactly," Greek lawyer Ilia Marinaki told reporters.
"On Saturday morning, when policemen started shooting against them, they decided to leave."
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Athens News Agency said the group was made up of three majors, three captains and two sergeant majors.
Turkey's Foreign Minister Mevlut Cavusoglu said Ankara had asked Athens to send the eight back following yesterday night's challenge to President Recep Tayyip Erdogan's rule by discontented soldiers in which more than 250 people died.
"We have requested Greece to extradite the eight traitors as soon possible," Cavusoglu was quoted as saying by HaberTurk television.
According to an official in the Greek National Defence General Staff, "the helicopter is scheduled to be sent back immediately to Turkey".
"As far as the asylum-seekers are concerned, we are going to proceed according to international law" Olga Gerovasili, the Greek government spokeswoman, said.
She said Athens was "in constant contact with the Turkish authorities," and would take into account the fact that "the asylum-seekers took part in a coup against the Turkish constitution".
Greek Prime Minister Alexis Tsipras today expressed his "support for the democratically elected" Turkish government.