Turkish authorities detained President Tayyip Erdogan's main political rival on Wednesday on charges including corruption and aiding a terrorist group, in what the main opposition party called "a coup attempt against our next president.

The arrest of Istanbul’s mayor, a popular opposition leader, marks a dramatic escalation in an ongoing government crackdown on dissenting voices in Turkey.

Turkey detained Istanbul mayor Ekrem Imamoglu, the main rival of President Tayyip Erdogan, on charges of corruption and aiding a terrorist group in what the main opposition party on Wednesday called "a coup against our next president".