A number Islamic books written by Fethullah Gulen have been confiscated along with several copies of the now-closed Sizinti magazine during an anti-drugs operation in Turkey’s southern province of Adana.

Anti-narcotics police in Adana’s Seyhan district raided a passage upon a complaint to seize opiate drugs on Wednesday. While four people were detained as part of the operation, police found bags of cannabis hidden in the secret holes in the passage.

State-run Anadolu news agency said police also seized several copies of Gulen’s books and old issues of the Sizinti magazine.

Turkish government blames Gülen movement for the July 15, 2016 coup attempt while the latter denies involvement. Books penned by Gulen and those by sympathizers of the movement were banned by government decrees issued under emergency rules.

Sizinti was shut down with a post-coup government decree.