Eighteen people have been taken into custody in simultaneous operations Thursday against what is known as the parallel state in 14 provinces, including Izmir and Kocaeli in the west and Sivas and Sanliurfa in the east.
The parallel state designates a clandestine group of Turkish bureaucrats and senior officials, allegedly embedded in the country's institutions, including the judiciary and the police.
The detainees are all alleged to be part of a "parallel state" conspiracy headed by Fethullah Gulen, a U.S.-based preacher who runs a network of schools and commercial enterprises in Turkey and around the world.
Police sources said early Thursday that the Izmir Public Prosecution Office issued a warrant for 25 people in a case of a military espionage.
The Izmir Public Prosecution office said Thursday that among the 25 suspects were high-ranking police officials as well as members of staff of the Scientific and Technological Research Council of Turkey (TUBITAK).
The suspects have been sent to the police department in Izmir.
The ongoing operation against the parallel state has resulted in the detention of dozens of police officers and the reassignment of hundreds of other officers across Turkey.