ANKARA/BALIKESIR, Turkey

Some 20 people including ex-air force employees were arrested across Turkey over suspected links to the Fetullah Terrorist Organization (FETO), the group behind the 2016 coup attempt in the country, according to judicial sources on Tuesday. 

Police squads held simultaneous operations in seven provinces including Istanbul, Izmir, and Diyarbakir, apprehending 15 suspects accused of communicating with FETO members through an organizational communication line, said the sources who asked not to be named, due to restrictions on speaking to the media.

The raids came after Ankara prosecutors issued arrest warrants for the suspects, with operations currently ongoing.

In a separate operation, five suspects accused of using the group’s encrypted messaging application, ByLock, were arrested in seven provinces on Tuesday after the Istanbul Public Prosecutor’s Office issued arrest warrants for 15 suspects.

Prosecutors also issued arrest warrants for 21 suspects as part of a probe into FETO’s underground structure in the country's universities.

Separately, prosecutors in the northwestern province of Balikesir issued arrest warrants for 11 suspects -- 8 of them being on-duty soldiers -- as part of a probe into the terror group's presence in the Turkish Armed Forces.

FETO and its U.S.-based leader Fetullah Gulen orchestrated the defeated coup of July 15, 2016, which left 251 people martyred and nearly 2,200 injured.

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

*Başak Akbulut Yazar from Istanbul contributed to the story.