Six former employees of one of Turkey’s oldest newspapers were sent back to prison on Thursday after a court upheld their convictions on terrorism-related charges in a high-profile case international rights defenders have slammed as a blatant attack on press freedom.

The group, which includes journalists, lawyers, a board member and an accountant who worked for Cumhuriyet newspaper, were all sentenced to prison terms of fewer than five years exactly one year ago, and had been free pending their appeal. A district appeals court last week rejected their petition and ordered the men to return to prison.

Columnists Guray Oz and Hakan Kara and award-winning political cartoonist Musa Kart were among those who entered prison in the northwest town of Kocaeli on Thursday. Kadri Gursel, an Al-Monitor columnist, and lawyer Bulent Utku have yet to receive their summons but could face re-arrest in the coming days, a source close to the matter said. All of the men are among the 18 people who were convicted after a court ruled that Cumhuriyet’s coverage had aided terrorist groups.

“Reporters Without Borders sees imprisoning these journalists again as a transgression of the rule of law and a cruel implementation that clearly harbors political retribution,” Erol Onderoglu, the watchdog’s representative in Turkey, told Al-Monitor.