At least 21 people were detained as part of an investigation into the Gulen movement followers in Zonguldak, on Wednesday.
Police carried out operations to detain the suspects in Kozlu, Kilimli and Ereğli districts.
Detainees included 10 females, among them several housewives and university students.
The prosecutor overseeing the investigation accuses the suspects of having used ByLock, a mobile application claimed to be the once-top communication tool among Gulen sympathizers.
Turkey survived a military coup attempt on July 15 that killed over 240 people and wounded more than a thousand others. The AK Party government along with President Recep Tayyip Erdoğan pinned the blame on the Gülen movement. The movement denies any involvement.