ISTANBUL (Reuters) - Turkish authorities have begun freeing some suspects arrested for involvement in a coup attempt after they found that thousands had been unwittingly re-directed to a messaging app used by the plotters, media outlets reported on Friday.

FILE PHOTO: People wave Turkey's national flags as they attend a ceremony marking the first anniversary of the attempted coup in front of the Turkish Parliament in Ankara, Turkey July 16, 2017. REUTERS/Umit Bektas

Turkey has identified 215,000 users of the ByLock messaging app and started investigating more than 23,000 of them. Ankara said many of those were re-directed to ByLock unwittingly via a different app developed by the plotters of the failed coup. An arrest warrant was issued for the developer of that app.

Ankara’s chief prosecutor said earlier this week that using ByLock remains one of the biggest indications of collaboration with the plotters of the failed putsch in which 250 people were killed.

But he said he would ask for the release of 1,000 suspects unless there was any other evidence against them.

Ankara prosecutor’s office said it would review the cases of 11,480 suspects who were re-directed to ByLock without their consent.

Private broadcaster NTV said 161 suspects in Istanbul, 27 in the capital Ankara, and 14 in southeastern province of Diyarbakir were freed. Cases against 36 others in northwestern Yalova province were being re-evaluated, it said.

The list of those to be released included a former Justice and Development Party (AKP) member of parliament and the coach of a soccer team.

An accountant from the opposition newspaper Cumhuriyet, who was in jail for 267 days, was also among those released. The case against 17 other employees of the newspaper continues.

Ankara said it would issue a decree calling for those released from prison to be returned to their jobs, state broadcaster TRT Haber said.

Authorities say ByLock was widely used by followers of U.S.-based cleric Fethullah Gulen, who the government blames for orchestrating the failed military coup in which 250 people were killed. Gulen has denied any involvement.

Since the coup attempt, more than 50,000 people, including civil servants and security personnel, have been jailed pending trial and some 150,000 suspended or dismissed from their jobs.

Rights groups say the crackdown has been exploited to muzzle dissent. The government says the measures have been necessary due to the security threats which Turkey has faced since the failed putsch.