ANKARA, Dec. 6 (Xinhua) -- Turkey on Tuesday arrested the chief adviser to the leader of the main opposition Republican People's Party (CHP) in ongoing probe into a coup attempt, Hurriyet Daily News reported.

Fatih Gursul, adviser to CHP chairman Kemal Kilicdaroglu, had reportedly used ByLock, an encrypted messaging application that was used by the Gulen movement.

Gursul, who is associate professor, was arrested at his residence in Ankara.

He is expected to be transferred to Istanbul for legal proceedings.

Fethullah Gulen, a U.S.-based Islamic preacher, is accused by the Turkish government of orchestrating the failed coup attempt on July 15.