Ekrem Imamoglu's hearing centers on insulting and threatening the chief Istanbul prosecutor. His imprisonment over unrelated charges of corruption and aiding a terrorist group sparked mass protests across Turkey.

Istanbul Mayor Ekrem Imamoglu, a leading rival of Turkey's President Tayyip Erdogan, will appear before a court on Friday for the first time since his high-profile arrest last month, over earlier accusations of insulting a prosecutor.

The imprisoned and ousted Istanbul mayor Ekrem İmamoğlu testified Friday at the opening of a trial over accusations of threatening a public prosecutor - one of several legal cases that could result in a prison sentence and a ban on holding public office.