A Turkish court ruled on Tuesday that civil society leader Osman Kavala will remain in custody pending the outcome of his trial on charges of seeking to overthrow the government, a rights group said.
Kavala is one of 16 people accused of orchestrating the "Gezi Park" protests of 2013 -- charges dubbed an absurd sham by critics.
However, the court agreed to release another defendant, researcher Yigit Aksakoglu while the trial is ongoing, according to rights group P24.
The next hearing is due on July 18.
The Gezi Park protests began over government plans to build on one of Istanbul's few green spaces.
It snowballed into a nationwide movement that marked the first serious challenge to President Recep Tayyip Erdogan's brand of Islamic conservatism and grandiose development projects.
The indictment seeks to paint the protests as a foreign-directed conspiracy with links to the Arab Spring, which, ironically, the Turkish government supported.
A respected figure in intellectual circles, Kavala is chairman of the Anatolian Culture Foundation, which seeks to bridge ethnic and regional divides through art, including with neighbouring Armenia, with which Turkey has no diplomatic ties.
He has been in jail since November 2017, becoming a symbol of what his supporters say is a crackdown on civil society.
"I was involved in projects contributing to peace and reconciliation. There is not a single piece of evidence or proof in the indictment that I prepared the ground for a military coup," Kavala told the court on Monday.
"The idea that Osman Kavala led the conspiracy is utterly outlandish and unsupported by any credible evidence," Emma Sinclair-Webb, the Turkey director of Human Rights Watch (HRW), told AFP.
There has been a renewed crackdown on dissidents since a coup attempt in 2016, blamed by the government on US-based Muslim preacher Fethullah Gulen, with thousands arrested and tens of thousands sacked from public sector, media and military jobs.
Six of the group are being tried in absentia after fleeing Turkey, including actor Memet Ali Alabora and dissident journalist Can Dundar.
Erdogan has linked Kavala to US billionaire George Soros, whose efforts to promote democracy around the world have made him a target for several authoritarian leaders.
Soros's Open Society Foundation, which ceased activities in Turkey last year, called Monday's trial a "political sham".