Turkish prosecutors in Ankara were questioning 27 generals on Monday, including an ex-Air Force commander suspected of being the coup ringleader, according to the state-run Anadolu Agency.
The suspects were rushed into the Ankara court under tight security and appeared to be handcuffed.
The Anadolu Agency said the group questioned includes former Air Force commander General Akin Ozturk who has been described as the ringleader of the foiled uprising.
Ozturk, who remained in active duty, has denied he was involved and insisted in local media he worked to quell the uprising.
The coup plotters sent warplanes firing on key government installations and tanks rolling into major cities, but the rebellion was quashed by loyal government forces and masses of civilians who took to the streets.
At least 294 people were killed and more than 1,400 wounded.