Turkish police have detained the strongest rival to President Recep Tayyip Erdogan, a move that experts say is aimed at removing all possible contenders ahead of the next presidential election and further stretching his rule.

The moves against Istanbul Mayor Ekrem Imamoglu and dozens of others could help extend President Recep Tayyip Erdogan’s two decades in power.

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".