Turkish authorities on Monday detained some two dozen police officers in new nationwide raids over an alleged plot to overthrow the Islamic-rooted government of President Recep Tayyip Erdogan.

Police conducted early morning raids in 16 cities across Turkey, including Istanbul as well as the western province of Izmir, and detained at least 20 police officers, private NTV television reported.

Among those arrested is Yakup Saygili, the former chief of the police anti-fraud unit, it added.

It was the fourth such wave of raids since July as the government cracks down on what Erdogan has described as a “parallel state” within the security forces.

Arrest warrants were issued for at least 34 officers accused of a number of offenses including illegally eavesdropping on top officials and attempting to overthrow the government.

Since July, dozens of police officers have been arrested and placed in custody on suspicion of forming a criminal organization and wire-tapping hundreds of people including Erdogan.

The new arrests appeared to represent a new offensive against the movement of Erdogan’s former ally Fethullah Gulen in the wake of a vast corruption scandal that broke late last year implicating Erdogan and his inner circle.

Erdogan has long accused followers of US-based Muslim cleric Fetullah Gulen of establishing a “parallel state” by using its sway in Turkey’s police and the judiciary and of concocting the vast corruption scandal.

Erdogan on Thursday moved from the office of prime minister to president after his August 10 election victory, with his close ally, former foreign minister Ahmet Davutoglu, taking the post of premier.

Erdogan had said Davutoglu was chosen due to his “determination to fight” the parallel state.