An appeals court in Turkey has upheld the convictions of 14 journalists and senior staff members of a prominent opposition newspaper.

Cumhuriyet newspaper said six staff members were ordered to jail because their appeals are exhausted, while those with longer sentences can appeal further to the supreme court.

An Istanbul court in April convicted the 14 of "aiding a terror group without being a member," handing down jail sentences ranging from 2½ to 7½ years.

Among the convicted were editor-in-chief Murat Sabuncu, board chairman Akin Atalay, prominent columnist Kadri Gursel and investigative journalist Ahmet Sik, who is now a member of parliament.

The case against Cumhuriyet was widely criticized as a crackdown on press freedom. Turkey ranked 157 out of 180 countries in Reporters Without Borders' 2018 index on press freedom.