The public prosecutor's offices in Istanbul and Ankara have issued arrest warrants for 87 people on Tuesday for their alleged links with the Gülenist Terror Group (FETÖ), according to judicial sources.

The Istanbul Chief Public Prosecutor's Office issued arrest warrants for 60 people who were accused of providing education consultancy to FETÖ members and using the ByLock encrypted messaging app. ByLock is an encrypted mobile phone application that was used by FETÖ members to communicate during and after the 2016 defeated coup.

Istanbul Police Department's counterterrorism unit launched a simultaneous operation across 28 provinces to apprehend the suspects.

The Ankara Chief Public Prosecutor's Office also issued arrest warrants for 27 former employees of the Youth and Sports Ministry as part of an investigation into the FETÖ terrorist network. So far, police in Ankara have arrested eight suspects while the search for more suspects remains ongoing, according to a police source, who wished to remain anonymous due to restrictions on talking to the media.

In a separate operation in central Konya province, police arrested 15 people for their alleged links to the "female wing" of the FETÖ group. Police nabbed three more suspects connected to an ongoing probe launched by the Konya Public Prosecutor's Office, the source added.

FETÖ and its U.S.-based leader Fetullah Gülen orchestrated the defeated coup of July 15, 2016, which left 250 people dead and nearly 2,200 others injured.

Ankara also accuses FETÖ of being behind a long-running campaign to overthrow the state through the infiltration of Turkish institutions, particularly the military, police and judiciary.