ISTANBUL (Reuters) - Turkish authorities issued detention warrants on Monday for 106 people believed to have worked as matchmakers for a network accused of orchestrating last year’s failed military coup, a spokesman for the Istanbul police said.

Sixty-two of the suspects had been detained in the operation centered in Istanbul and spread over 20 other provinces, he said. Operations to locate the rest were ongoing.

The suspects were “marriage officials” for supporters of the U.S.-based cleric Fethullah Gulen, who the Turkish government says was behind the failed July 2016 coup, the spokesman said. Gulen denies any involvement in the coup attempt.

They were believed to have helped set up arranged marriages for some of Gulen’s followers, he said. Turkish officials say the Gulen network closely monitored the personal and professional lives of some supporters, including their education, careers and marriages.

Turkish police and state intelligence officials identified the suspects in a joint operation using conversations traced on ByLock, an encrypted messaging application commonly used by Gulen’s supporters, the spokesman said.

Turkey has identified 215,092 users of ByLock and has launched investigations into 23,171 of them, the interior minister said last month.

More than 50,000 people, including security officials, military personnel and civil servants, have been detained in the aftermath of the coup.

The crackdown has alarmed Turkey’s Western allies and rights groups, who say President Tayyip Erdogan is using the coup as a pretext to muzzle dissent.

The government says the measures, taken under emergency rule that was imposed after the coup, are necessary due to the security threats Turkey faces.