ANKARA (Reuters) - A Turkish court upheld life sentences on Tuesday for prominent journalist Ahmet Altan and five others, the state-run Anadolu news agency said, after they were sentenced in February on charges of aiding plotters of a failed military coup in 2016.

Ahmet Altan, his brother Mehmet Altan and four other journalists were previously sentenced to life in jail for alleged links to the network of U.S.-based cleric Fethullah Gulen, accused by Ankara of orchestrating the 2016 coup attempt.

Mehmet Altan was released from prison in June, but his sentence was also upheld on Tuesday, after a penal court rejected the constitutional court’s request for his release.

The Altans’ trial has underscored concerns about human rights and press freedom in Turkey under a post-coup crackdown, as well as worries over the independence of the judiciary under President Tayyip Erdogan.

Since the abortive putsch, more than 50,000 people have been jailed and 150,000 sacked or suspended from their jobs, while more than 120 journalists have been detained and about 180 media outlets shut down.

Rights groups and Turkey’s Western allies have voiced concern that the government has used the putsch as a pretext to quash dissent, but the government has said the measures were necessary due to the gravity of the security threats it faces.

Ahmet Altan was charged over comments he made the day before the coup attempt, when he told a television show: “Whatever the developments were that led to military coups in Turkey, by making the same decisions, Erdogan is paving the same path”.

On the same programme, Mehmet Altan referred to “another structure” within the government that was closely watching developments to “take its hand out of the bag”.

Prosecutors said the brothers’ comments were coded messages to call Gulen’s followers to action, and were charged with “violating the constitution”, according to Anadolu.

All six journalists in the case are serving aggravated life sentences, which means they are not eligible for parole and cannot be included in future amnesty decisions.