ANKARA (Reuters) - Turkish authorities issued detention warrants on Friday for 79 former teachers, the state-run Anadolu news agency said, as part of a widening crackdown since last year’s failed coup attempt.

The teachers were formerly employed at schools allegedly linked to the U.S.-based cleric Fethullah Gulen, accused by Ankara of orchestrating last July’s abortive putsch, Anadolu said. The schools were shut down after the coup attempt.

Gulen, who has lived in self-imposed exile in Pennsylvania since 1999, denies involvement.

Anadolu said security forces were carrying out operations to capture the suspects in Ankara, where thousands of teachers from across the country arrived to visit the mausoleum of Mustafa Kemal Ataturk, founder of modern Turkey, to celebrate the national teachers’ day.

Since the abortive coup, more than 50,000 people have been jailed pending trial over alleged links to Gulen, while some 150,000 people have been sacked or suspended from jobs in the military, public and private sectors.

Rights groups and some of Turkey’s Western allies have voiced concern about the crackdown, fearing the government is using the coup as a pretext to quash dissent.

The government says only such a purge could neutralize the threat represented by Gulen’s network, which it says deeply infiltrated institutions such as the army, schools and courts.