Turgut Öker, honorary chairman of the Confederation of European Alevi Unions (AABK), was detained on Friday morning upon his arrival at the İstanbul airport, Deutsche Welle Turkish service reported.

Öker was reportedly released after an interrogation by an İstanbul prosecutor. He had arrived from the German city of Cologne to attend a panel discussion organized by an Alevi foundation in İstanbul.

He was accused of spreading terrorist propaganda, according to Fuat Ateş, another German-based Alevi leader who spoke to DW.

Ateş said this was the fifth time Öker had been detained in Turkey since 2004, each time based on similar terrorism-related charges.

“We consider the repeated detentions of our honorary chairman to be part of an intimidation campaign against the Alevi movement in Turkey,” Ateş said.

Turkey has been criticized and even fined in the past by the European Court of Human Rights (ECtHR) for discriminating against its Alevi minority and their places of worship.