Six retired generals testified on Thursday in an Ankara court as part of an ongoing probe into the 1997 coup that ousted an Islamic-leaning government, local television reported.
They were summoned to testify a day after four ex-generals including a navy chief were detained pending trial for their alleged role in the coup, the latest development in a standoff between the military and Turkey's current Islamist-rooted government.
Prosecutors are preparing an indictment for around 90 suspects, including 60 retired and active military officers, as part of the probe launched in 2011.
The events of February 28, 1997 are widely referred to in Turkey as a "post-modern coup" since they involved no troops and the deposed cabinet was not replaced by a military administration.
Then prime minister Necmettin Erbakan was forced to step down after a series of warnings from the army, which ordered scores of tanks to roll through the streets of Ankara in what was seen as a show of power against the government.
The once-powerful military, considered the self-appointed guardian of Turkish secularism, has staged four coups in half a century.
Tensions have been rising for years between the military and the current government of Prime Minister Recep Tayyip Erdogan, a disciple of Erbakan.
Hundreds of suspects, including army officers, journalists and lawmakers, are being tried in separate cases over their alleged roles in plots to topple Erdogan's Justice and Development Party (AKP), which has sought to decrease the army's influence in politics.
In September more than 300 retired and active military officers received prison sentences of up to 20 years after the court ruled that a military exercise dubbed "Sledgehammer" in 2003 was an undercover coup plot.
Pro-government circles have praised the investigations as a step toward democracy but critics have branded them witch-hunts aimed at stifling opposition.