Local media said prosecutors were demanding life in prison for five officers.
Turkish prosecutors on Wednesday indicted 17 more people on charges of plotting to topple the AK Party government, and local media said prosecutors were demanding life in prison for five officers.
More than 200 people, including military officers, lawyers and politicians, have been arrested since the "Ergenekon" case came to light two and a half years ago.
Prosecutors accuse the group of planning to sow chaos through bombings and attacks across Turkey to force the army to step in and topple the government.
The state-run Anatolian news agency said Wednesday's 300-page indictment was connected to a large cache of weapons discovered in an Istanbul neighbourhood in April.
Local media said the indicted included two lieutenant colonels, two majors and a retired major, for whom prosecutors are demanding life in prison.
The military has denied any links to Ergenekon, an secularist ultra-nationalist group.
The head of Turkey's armed forces, General Ilker Basbug, on Monday angrily denied a recent newspaper report accusing the military of plotting to overthrow the government.
Basbug also said coups were "a thing of the past".
/World Bulletin/