The United States says it is "deeply disturbed" over the arrest by Turkish authorities of a local employee working at its consulate in Istanbul.
The state-run Anadolu news agency says the employee was remanded in custody by an Istanbul court late on October 4 on accusations of links to the group of U.S.-based cleric Fethullah Gulen, who Ankara says orchestrated last year's failed coup.
The man, identified in the local media by the initials M.T., has been formally charged with espionage and seeking to overthrow the Turkish government, Anadolu said.
"The United States government is deeply disturbed by the arrest of a locally-employed staff member," the U.S. embassy in Ankara said in a statement on October 5.
"We believe these allegations to be wholly without merit," it said.
Turkey has pressed Washington for Gulen's extradition. The cleric has denied any link to the coup attempt.
Since October 2, Turkey has detained 291 people on suspicion of links to Gulen, Anadolu reported.