ISTANBUL (Reuters) - Turkish prosecutors issued arrest warrants for 243 people, including 92 teachers, in operations targeting suspected followers of the Muslim cleric the government blames for a failed 2016 coup, state-run Anadolu news agency said on Friday.

The teachers, targeted in an operation in 20 provinces, had worked in schools previously closed for alleged links to the cleric, Fethullah Gulen, Anadolu said.

In another operation launched in central Turkey’s Konya and spread across more than three dozen other provinces, authorities issued warrants for 84 people suspected of similar ties, Anadolu.

Another 57 people were ordered detained by the Istanbul chief prosecutor for using ByLock, an encrypted messaging app that the government says was widely used by Gulen’s network, Anadolu said.

Ankara says Gulen and his network were behind the failed coup attempt of July 2016 during which 250 people were killed. Gulen has denied involvement.

More than 50,000 people have been jailed and over 150,000 sacked or suspended from the military, schools and the public institutions in a crackdown following the coup attempt.

Critics say Erdogan is using the failed coup as a pretext to quash dissent. Turkey says the strict measures are required given the security threats it faces.