The prosecutor responsible for the ongoing terror probe into the executives and writers of Turkey's Cumhuriyet daily asked Friday for the imprisonment of all suspects for 15 years each.

The 13 suspects, among whom are also journalist Ahmet Şık, the daily's editor-in-chief Murat Sabuncu and Cumhuriyet CEO Akın Atalay, are accused of "aiding an armed terrorist organization while not being a member of it."

The prosecutor read out his indictment during the hearing, which was held by the Istanbul 27th High Criminal Court near the Silivri Penal Institution.

A court previously ordered the conditional release of Sabuncu and Şık, who were accused of having links to the Gülenist Terror Group (FETÖ).

Atalay, who maintained a popular FETÖ-linked Twitter account, was ordered to remain in prison.

The majority of the evidence in the indictment comes from social media posts, along with allegations that staff members had been in contact with users of ByLock, an encrypted messaging app the government says FETÖ members used.

Founded in 1924, Cumhuriyet is the oldest newspaper in Turkey that is still in business.

Cumhuriyet had long followed a secular, left-wing, republican editorial policy with a nationalist tone. However, in recent years, the paper drew ire from some of its reader base for adopting a tone that they claimed supports the PKK and, most recently, FETÖ.