A Turkish court on Monday handed down lengthy jail sentences to at least 20 university students over their links to the Gulen group, which the Turkish government accuses of masterminding a coup attempt in 2016. The group denies any involvement.

According to the Turkish media, one of the students get 10 years in prison while two others were given 8 years and 9 months over “membership in a terrorist organization.” The remanings are given 1 year to 3 years prison sentences for having used ByLock mobile app.

Before it was pulled off the market, ByLock was an encrypted mobile app that Turkish government sees as a communication tool among followers of the Gulen movement. The government accuses Gulenists of masterminding the July 15, 2016 failed coup while the group denies involvement. Interior Minister Suleyman Soylu said  that at least 510,000 people have been detained over Gulen links since the summer of 2016.