Can Dundar, editor-in-chief of Turkish daily newspaper Cumhuriyet, and Erdem Gul, the newspaper's Ankara bureau chief, were arrested Thursday night after three hours of questioning at an Istanbul court, according to Turkey's semiofficial Anadolu Agency.
The two journalists have been charged with obtaining and revealing confidential state security information for political or military espionage, and with willfully aiding an armed terrorist organization, the news agency reported.
A Turkish government official, reached by CNN for comment, had little to say.
"This is a judicial process, and we are following it," said the official, who declined to be identified either by name or department.
Group: Turkey 149th in terms of press freedom
Turkey is said by international organizations to have a poor record on press freedom. Reporters Without Borders rates the country 149th of 180 countries
in its 2015 Press Freedom Index.
And in 2013, the Committee to Protect Journalists said more journalists were in prison in Turkey -- 40 -- than in any other country. The number has since dropped to fewer than 10.
"We have been arrested," Dundar tweeted at 11 p.m. Thursday.
Videos of the arrest were shared on Periscope.
In a video before the pair's arrest, Dundar said they were defending freedom of press and "the right of the people to get information."
But Hadi Salihoglu, the Istanbul public prosecutor, disagreed.
"This investigation has nothing to do with 'freedom of press,' which is guaranteed under the constitution and there were no violations of people's rights and freedoms," Salihoglu said, Anadolu Agency reported.
A pro-opposition newspaper
In June, Cumhuriyet published leaked video footage that purported to show the county's intelligence agency sending weapons to Syria.
Cumhuriyet is a secularist and pro-opposition newspaper that has been in circulation since 1924.