The Istanbul court also ordered the arrest of retired colonel Levent Goktas, while it released Huseyin Buzoglu, the lawyer of retired Gen. Tuncer Kilinc and writer Ergun Poyraz who were detained earlier in the operation.

Kucuk and Goktas were charged with "membership of a terrorist organization" and sent to jail pending trial.

In last week's Ergenekon operation, 33 people were detained; the court arrested 17 of the suspects and released 16.

The Ergenekon probe was launched in 2007 after the discovery of hand grenades at a house in Istanbul. Then it was widened to crackdown on an "illegal gang" allegedly planning to stage a series of incidents that would eventually provoke a military coup.

More than 100 people were detained and around eighty of them were formally charged for "forming a terrorist organization or being a member of a terrorist organization."

But the probe became controversial when the first indictment failed to satisfy the expectations of concrete evidence that would match the allegations.

The detainments of high-profile opponents of the Justice and Development Party (AKP) have fuelled charges that the ruling party is launching a witch hunt against its opponents.