Police arrested 28 suspects across Turkey as part of an ongoing investigation into the Fetullah Terrorist Organization (FETO), according to a police official.
Earlier, the Chief Public Prosecutor's Office in Ankara had issued arrest warrants for 81 people for alleged use of ByLock.
ByLock is a mobile app that had been allegedly used by FETO members during the July 15, 2016, defeated coup.
The app is believed to have been cracked by Turkish security agencies, allowing them to identify tens of thousands of apparent FETO supporters.
The countrywide arrests were made after police carried out Ankara-based operations against FETO in 13 provinces.
Suspects worked at FETO-linked schools and private teaching institutions, the official, who spoke on condition of anonymity due to restrictions on talking to the media, said.
Turkey accuses FETO of a long-running campaign to overthrow the state through the infiltration of Turkish institutions, particularly the military, police, and judiciary.
FETO and its U.S.-based leader Fetullah Gulen orchestrated the defeated coup of July 15, 2016, which left 250 people martyred and some 2,200 injured.
