A Turkish court on Tuesday ordered six human rights activists including Amnesty International's Turkey director to remain in custody, in a case the NGO has called a "travesty of justice."

Turkey director Idil Eser was detained on July 5 along with seven other activists and two foreign trainers during a digital security and information management workshop on Buyukada, an island south of Istanbul.

"Six were remanded in custody and four released on judicial control," Amnesty International's Turkey researcher Andrew Gardner told AFP.