A Turkish man named Metin Can Yılmaz has filed a criminal complaint against Tesla CEO Elon Musk over alleged Gulen links after Musk urged his Twitter followers to use the encrypted messaging app, Signal, the Turkish media reported.

“Use Signal,” the Tesla Inc. chief executive officer wrote on Twitter on Jan. 7, apparently referring to the encrypted messaging service.

Yılmaz’s complaint came as a clear reference to the Turkish government’s hostility towards ByLock, an encrypted messaging app which is considered by the authorities a secret tool of communication among supporters of the Gülen group since a coup attempt on July 15, 2016.

According to a statement from the interior ministry in March 2019, 95,310 people were charged over alleged use of the ByLock application. In its technical report, which courts use as basis for their decisions, the Turkish intelligence agency stated that 60,473 defendants had at least one message posted using ByLock while 34,837 defendants had not posted any message using the application.

The Gülen grouğ is accused by the Turkish government and President Recep Tayyip Erdoğan of masterminding the failed coup and is labeled a “terrorist organization,” although it denies involvement in the coup attempt.