Turkey's former military chief Ismail Hakki Karadayi was arrested on Thursday for his alleged role in a 1997 coup that forced an Islamic-leaning government out of power, Anatolia news agency reported.
The retired general is later expected to testify before an Ankara court as part of the investigation that was launched in 2011 and led to the arrests of dozens of other military officers.
Karadayi was the head of the military chiefs of staff in 1997, the last time Turkey's once all-powerful military was involved in changing the government when it forced the Islamic-rooted premier Necmettin Erbakan to step down.
The events of 1997 are popularly referred to in Turkey as a "post-modern coup" since it involved no troops and the deposed cabinet was not replaced by a military one.
The case forms another link in the chain of probes into coups and coup plots in Turkey's history, where four governments have been toppled in half a century by the military, the self-appointed guardian of Turkish secularism.
Tensions have been rising for years between the military and the government of Prime Minister Recep Tayyip Erdogan, a disciple of late premier Erbakan, and his Islamic-rooted Justice and Development Party (AKP), in power since 2002.