27 policemen, including senior officers were sent to the Istanbul criminal court on charges of an attempted coup and political and military espionage related to an ongoing "parallel state" probe.
The suspects were among 29 people detained across 20 Turkish provinces Monday, which included the former vice-head of Istanbul Security Department.
The remaining two suspects that include the former chief of Istanbul Organized Crime Control Bureau will be sent to the prosecutor's office once police complete their questioning.
The suspects were detained on charges of establishing and being a member of a criminal organization, political espionage, forgery, illegal storage of personal data and deleting computer data.
The "parallel state" is an alleged group of Turkish bureaucrats and senior officials embedded in the country's institutions, including the judiciary and the police, which allegedly wants to undermine the current Turkish government.
The government alleges that the clandestine network is run by the U.S.-based preacher Fetullah Gulen and that his so-called Gulen movement is responsible for masterminding a plot to overthrow the elected Turkish government.
Turkey wants Gulen to be extradited from the U.S., where he has lived since 1999. An Istanbul criminal court had issued an arrest warrant for Gulen as part of a probe into the parallel state operation.