A leading suspect in the July 2016 attempt to overthrow the Turkish government is living in a safe house controlled by Germany’s intelligence agency, said Abdulkadir Selvi, a columnist known for his close ties to Turkey’s ruling Justice and Development Party (AKP).

Adil Öksüz, a former theology professor at Sakarya University, is accused of being a senior member of the Gülen movement and coordinating the coup attempt in which some 250 people were killed before it was quashed by mass protests.

"Adil Öksüz is said to have been held in the safe houses of the Federal Intelligence Service (BND) because he is a cosmic name," Selvi said on Monday, referring to NATO’s top level of security classification – Cosmic Top Secret – that is applied to information the unauthorised disclosure of which would cause exceptionally grave damage to the alliance.

Selvi did not say where the safe house was.

Video footage shows Öksüz at the Akıncı military base, from where the putsch was launched, on the night of the coup. He was captured trying to flee the base then released two days later and has been a fugitive since.

Turkish Interior Minister Süleyman Soylu said on Sunday that the Turkish government had knowledge of Öksüz’s whereabouts, but did not provide further information.

State-run Anadolu news agency has reported that Öksüz was living in Germany.