The former Istanbul anti-terror police chief, himself among those detained and led away in handcuffs, said the incident was entirely political, coming just a few weeks ahead of a presidential election in which Mr Erdogan is standing.
Police conducted raids in 22 provinces across Turkey yesterday and officers involved in a separate government corruption probe which emerged in December and led to the departure of four ministers were among those detained.
The officers were accused of making up an investigation into an alleged terrorist group as a pretence to tap the phones of Mr Erdogan, ministers and the head of the national intelligence agency.
Istanbul chief prosecutor Hadi Salihoglu said: "The order was given for the capture and detention of 76 police officers who were investigating the group named selam-tevhid but whose actual aims were spying."
He said the case, targeting 251 people, had been dismissed due to a lack of evidence after a three-year investigation during which 2,280 people were wire-tapped.