Istanbul Mayor Ekrem İmamoglu has appeared before police for questioning on terror-related charges a day after his interrogation over corruption allegations.

Protests against the detention of Istanbul's mayor grew on Friday and turned increasingly tense, Turkey's biggest show of civil disobedience in more than a decade after President Tayyip Erdogan warned it would not be tolerated.

Turkey's authoritarian crackdown on political opposition continued Thursday with 37 people arrested for social media posts deemed "provocative." The posts came after the arrest of opposition leader Mayor Ekrem Imamoglu.