Operations were launched simultaneously in 29 provinces and 33 suspects have been detained so far under arrest warrants issued by the Chief Public Prosecutor's Office in Istanbul, Xinhua quoted local media reports as saying.
Among the captured are Fatmanur Gulen, the niece of Fethullah Gulen, leader of the Gulen network who is living in the US, and Belkis Nur Tetik, the sister-in-law of Adil Oksuz, an alleged mastermind of the failed coup.
Turkey blames the Gulen network for the putsch in July 2016 that left 250 people dead and nearly 2,200 others injured, and has been pushing for Gulen's extradition.
More than 150,000 people have been dismissed or suspended from their posts while over 55,000 others were arrested in the ongoing investigation.
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