President Erdogan's purge of public sector staff with alleged links to US preacher Fethullah Gulen has reached the secret service, one of the country's most powerful institutions.

Dozens of staff at Turkey's secret service have been sacked as President Recep Tayyip Erdogan continues his purge of suspected "coup-plotters".



The National Intelligence Organisation (MIT) spy agency has fired 87 staff and suspended 141 personnel following an internal probe over links to US cleric Fethullah Gulen, who Ankara believes was behind the July 15 attempted putsch.



Criminal complaints have been lodged against 52 staff, Anadolu agency reported, and the 87 expelled employees will not be allowed to work in another state institution.



Turkey has arrested, sacked or suspended tens of thousands of people from state institutions in the wake of the attempted coup - but this was the first announcement of dismissals from the spy agency.



The MIT is one of Turkey's most secretive but powerful organisations, handling issues ranging from internal security to foreign policy.



Turkey's secret service was widely criticised for not warning authorities about the coup bid.



Erdogan publicly claimed intelligence lapses had helped the would-be military coup.



The Turkish leader had admitted he himself found about the coup, not from the intelligence service, but from his brother-in-law, and that he had been unable to reach MIT chief Hakan Fidan on the night of the putsch.



Speculation that the former army sergeant would be in the firing line was short-lived when a picture of a previously clean-shaven Fidan emerged, showing him in a meeting with the president in the aftermath of the coup with a moustache.



Several top ministers, including Foreign Minister Mevlut Cavusoglu, have grown facial hair in recent months in what is widely seen as a sign of loyalty to the moustachioed leader.



Two weeks after the coup, Erdogan announced he wanted to put the intelligence agency under the direct command of presidency - a constitutional change which would require opposition support.



Earlier this month, 8,000 security personnel were dismissed as part of the purge.



The government has asked US authorities to extradite Gulen to "face justice" in Ankara.



The preacher, who lives in self-imposed exile in Pennsylvania, has denied any involvement in the putsch.



