The operation was focused on the central Turkish province of Konya, with police carrying out simultaneous raids at addresses across 27 provinces, state-run Anadolu news agency reported.
Twelve of the 70 suspects had previously been expelled from the Turkish armed forces, Anadolu said.
Police operations to detain suspects accused of links to the Islamic preacher Fethullah Gulen have been a near daily occurrence since the failed putsch of July 15, 2016, in which Gulen has denied any involvement.
Since then more than 50,000 people, including thousands of security personnel and civil servants, 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 coup, in which 250 people were killed.