Nine people have been detained so far, Anadolu news agency said, adding that the suspects were accused of using a messaging app allegedly used by Gulen to mobilise followers in Turkey, and of belonging to a “terror” group.
Thousands of people have already been arrested in Turkey for using the Bylock messaging app, which the authorities say was used by Gulen supporters to coordinate actions ahead of the plot.
The latest arrests come amid growing alarm over press freedom in Turkey under President Recep Tayyip Erdogan, in particular because of the state of emergency imposed in the wake of the failed July 2016 coup which remains in place.
Gulen, an Islamic preacher who lives in the American state of Pennsylvania, denies any link to the botched putsch.
Those detained include a former columnist for the Turkiye daily, Ahmet Sagirli, and the current website editor at the leftist opposition Birgun daily, Burak Ekici.
Turkey ranks 155 on the latest Reporters Sans Frontieres (Reporters Without Borders) world press freedom index, below Belarus and the Democratic Republic of Congo.
According to the latest figures from the P24 press freedom website, there are 164 journalists behind bars in Turkey, most of whom were detained under the state of emergency.
In one of the highest profile cases, 17 staff from the Cumhuriyet daily — one of the few voices in Turkey’s media to oppose Erdogan — last month went on trial for aiding “terror” groups.
While most of the suspects in that case have been released from pre-trial detention, four Cumhuriyet journalists, most of whom have been held for eight months, remain behind bars.
The crackdown has also affected foreign reporters; freelance French journalist Loup Bureau was detained last month on charges of links to a Kurdish militia that Ankara regards as a terror group.