The US has voiced concern about the arrest of two Turkish journalists on espionage and treason charges.

“We are troubled by the pre-trial arrest of senior editors of the respected Turkish newspaper Cumhuriyet," US State Department Deputy spokesperson Mark Toner said in a statement.

"The investigation, criminal charges, and arrest raise serious concerns about the Turkish government’s commitment to the fundamental principle of media freedom,” Toner said.

On Thursday, Cumhuriyet newspaper Editor-in-Chief Can Dundar and the daily’s Ankara representative Erdem Gul were arrested on charges of espionage and treason after the outlet published photos of Turkish trucks carrying weapons bound for Syria.

"These events are only the latest in a series of judicial and law enforcement actions taken under questionable circumstances against Turkish media outlets critical of the government," Toner said.

Washington urged Ankara to ensure that all individuals and organizations, including the media, can freely express different views and criticism.