Eighteen people who were claimed to be using ByLock, a smart phone messaging application, were arrested on Friday as part of a witch-hunt targeting the Gülen movement.

Turkish prosecutors claim that ByLock is the top communication tool among members of the Gülen movement, which the government accuses of masterminding a July 15 coup attempt. Critics, however, have blasted the government for detaining thousands simply for using a mobile application.

A Kayseri court on Friday ruled for the arrest of the 18 people who had been earlier detained.

Labor and Social Security Minister Mehmet Müezzinoğlu told reporters in Bursa on Sept. 14 that the Turkish intelligence agency had determined the identity of nearly half of the 180,000 users of ByLock in Turkey.