Mehmet Çek, the Sabah newspaper’s representative in Switzerland, was taken into custody by police at his home, according to several reports on Turkish media.
He announced the news via his Facebook account on Tuesday.
No details were provided as to the reasons for Çek’s detention, although it was reported that he will soon appear before a prosecutor.
His computer, mobile phone and numerous documents were seized by Swiss authorities, the reports said.
Once described by the Tages Anzeiger newspaper as “Turkish President Recep Tayyip Erdoğan’s most fervent supporter in Switzerland,” he previously came to public attention when he protested Can Dündar, a Turkish journalist critical of the Ankara government living in exile, during a panel discussion at the University of Zurich.
“You can fool this crowd, but the people of Turkey know what a traitor you are,” he had said to Dündar.
In March 2017 he was sentenced by a Swiss court to 30 days in jail and 860 Swiss francs for recording phone calls and messages without permission.