An Istanbul Court of Appeals on Tuesday upheld the life sentences of six individuals, including prominent journalists Ahmet Altan, Mehmet Altan and Nazli Ilicak, on charges of assisting the plotters of a failed military coup in 2016.

The journalists were originally sentenced in February, along with 221 other defendants [JURIST report], and appealed [Al Jazeera report] to the high court for their release. All defendants were accused of being linked to a US-based religious leader Fethullah Gulen [CNN profile], who is accused of establishing and orchestrating the 2016 coup that killed more than 300 people and injured nearly 2,200 others.

Since the 2016 coup the Turkish government has been carrying out purges and arrests aimed at removing Gulen supporters from state institutions and other parts of society.

Turkish President Recep Tayyip Erdoğan [CNN profile] has previously called on the US and former president Barack Obama to either arrest or extradite Gulen from his Pennsylvania home.

“Dear Mr. President…You didn’t listen. I call on you again, after there was a coup attempt. Extradite this man in Pennsylvania to Turkey! If we are strategic partners or model partners, do what is necessary.”

International rights groups, as well as many of Turkey’s European allies, view the measures as arbitrary, claiming that the government is using the coup attempt to silence opposition in the country.

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