A Turkish court on Sunday charged two former policemen with illegally eavesdropping on President Recep Tayyip Erdogan following their extradition from Romania, state-media said.
Sedat Zavar, a former police chief, and Ilker Usta, were detained at Istanbul airport late Saturday after their arrival on a flight from Bucharest, the Anatolia news agency reported.
The court in Istanbul formally charged the two policemen with "forming a crime syndicate", "violating privacy" and "illegally obtaining personal information," Anatolia said.
The police officers, who were placed in pre-trial detention, are expected to appear in court on May 4 and face up to 36 years in jail if found guilty.
The detentions are a part of an intensifying crackdown against followers of US-based preacher Fethullah Gulen, accused by Erdogan of setting up a "parallel state" seeking to oust him from power and of concocting a corruption scandal that rocked the government in late 2013.
The authorities accuse police of bugging Erdogan and other top officials at the behest of Gulen, whose extradition is being sought by Turkey.
Since becoming president in August 2014 after serving as prime minister since 2003, Erdogan has intensified his offensive against Gulen followers.
The authorities have conducted raids against dozens of police officers accused in the spying case and others in the police force and the judiciary suspected of being Gulen supporters.
Erdogan described the two detained policemen as "spies" and said: "Why did you flee if you were innocent? You fled to Romania but you were caught there.
"You had been employed to serve the prime minister... When did you set out to become a spy?" he told a rally in Istanbul.
"We told them we would pursue them (Gulen supporters) into their lairs. We will find whoever is behind them no matter where they go."