ANKARA (Reuters) - A Turkish appeals court upheld the convictions of journalists and executives from the opposition newspaper Cumhuriyet, a case which has raised concerns about media freedom under President Tayyip Erdogan.

Headquarters of Cumhuriyet newspaper, an opposition secularist daily, is pictured in Istanbul, Turkey, October 31, 2016. REUTERS/Murad Sezer

Cumhuriyet said on Tuesday an appeals court had ruled the original trial was lawful and approved the convictions against its employees.

Fourteen staff of Cumhuriyet - one of the few remaining voices critical of the government - were jailed last year on charges of terrorism and supporting U.S.-based cleric Fethullah Gulen, blamed for organizing 2016 attempted coup.

All the accused denied the charges against them.

Human rights organizations have voiced increasing concern about media freedom in Turkey, accusing Erdogan of using the abortive putsch as a pretext to quash dissent.

Journalists Hakan Kara and Guray Oz, cartoonist Musa Kart, lawyer Mustafa Kemal Gungor, board member Onder Celik, and accountant Emre Iper will return to prison to complete their sentences, Cumhuriyet said. Under Turkish law, sentences under five years cannot be appealed further.

“The government, which is expected to produce solutions for the crises that we are going through, has spoken: lock the cartoonist up again!” Kart wrote in Twitter.

“Yes it’s time for me to get going, jail is on the horizon. Take care...,” he added.

“Thankfully I had completed the final edits to my novel. We will not be seeing each other for a while. Bye,” tweeted Guray Oz, the readers’ ombudsman for Cumhuriyet.

Editor-in-chief Murat Sabuncu, prominent journalist Ahmet Sik, Hikmet Cetinkaya, Orhan Erinc, Akin Atalay and Aydin Engin, all jailed for more than five years, will have to return to prison pending their appeal to a higher court, the paper added.

Journalist Kadri Gursel and lawyer Bulent Utku will not go back to prison due to time already served.

Since the failed coup, more than 77,000 people have been jailed pending trial, while about 150,000 civil servants and military personnel have been sacked or suspended from their jobs. Widespread operations and arrests are still routine.

Authorities ordered the arrest of 311 people, including 53 military personnel, in three separate operations across Turkey, the Istanbul prosecutor’s office said in a statement.