Gen. Ismail Hakkı Karadayı, a former chief of general staff, is the third military official detained in the so-called "Feb. 28 process" that led to the resignation of Prime Minister Necmettin Erbakan in 1997, Hurriyet Daily News reported Thursday.
Karadayi's arrest came after another general arrested in the investigation, Cevik Bir, accused him in an 11-page complaint of the West Study Group, or BCG.
Karadayi has denied he knew anything about the group, a group of military officers who reportedly monitored the government and illegally kept records on the private lives of hundreds of thousands of Turks, the report said.
Gen. Ilker Basbug, another former chief of general staff, also has been arrested in the investigation into whether an alleged ultra-nationalist group planned to topple the government.
The Feb. 28 process is named after the Feb. 28, 1997, meeting of the Turkish National Security Council during which military officials are suspected to have planned the coup, the report said.