Twenty-one schoolteachers who were claimed to be using ByLock, a smart phone messaging application, were arrested as part of a witch-hunt targeting the Gülen movement, on Monday.

Turkish prosecutors claim that Bylock is the top communication tool among the members of Gulen Movement, which the government accuses of mastermind the July 15 coup attempt. Thousands have so far been arrested for using the application.

A Kocaeli court ruled for the arrest of 21 out of 25 teachers who were detained earlier while the remaining four were released pending trial.

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 the 180,000 users of ByLock in Turkey.

Opening an account at Bank Asya after the Dec.17 and Dec. 25 corruption operations and using the ByLock applications are mentioned as the basic criteria for pursuing the witch-hunt against the Gülen movement.

The movement denies any involvement in the coup attempt.

More than 100,000 people have been purged from state bodies, nearly 43,000 detained and 24,000 arrested since the coup attempt. Arrestees included journalists, judges, prosecutors, police officers, doctors, court personnel and even a comedian.