Eleven human rights activists, including the two local heads of Amnesty International, have gone on trial in Turkey, accused of belonging to and aiding terror groups in a case that has increased concerns over Turkey's authoritarian regime under President Recep Tayyip Erdogan.
Ten of the activists, including Amnesty's Turkey director Idil Eser, German national Peter Steudtner and Swede Ali Gharavi, were arrested while attending a digital security training workshop at a hotel on an island off Istanbul in July.
They are accused of plotting an uprising and charged with aiding Kurdish and left-wing militants as well as the movement led by US-based cleric Fethullah Gulen, blamed for last year's coup attempt. They face up to 15 years in prison if found guilty.
Amnesty's Turkey chairman Taner Kilic, who was jailed separately in June, is appearing in court in the city of Izmir for alleged links to Gulen. He is accused of using an encrypted mobile messaging application allegedly used by Gulen's network.
Human rights groups say the defendants have been accused of "trumped up" charges.
"There is not a shred of evidence against the 11 human rights defenders on trial today," Andrew Gardner, Amnesty's Turkey researcher, told the Associated Press. "At the very least, our expectation and our hope is that they will be released from prison."
Mr Gardner added: "It's been a very difficult situation for all human rights organisations in Turkey for some time. But for 11 human rights defenders to be picked up after a routine human rights seminar is an escalation and repression in Turkey."
The trial is one of several cases that have deepened a rift between Turkey and European nations, notably Germany, which considers Mr Steudtner and some 10 other German or German-Turkish citizens jailed in Turkey to be political prisoners.
Turkey has arrested more than 50,000 people since the failed coup and sacked at least 110,000 others from government jobs. The crackdown was initially launched to deal with alleged coup-plotters but was expanded to include other government opponents, such as academics, journalists and legislators, critics say.
"These two trials will be an acid test for the Turkish justice system and will demonstrate whether standing up for human rights has now become a crime in Turkey," said John Dalhuisen, Amnesty International's director for Europe.