Turkish riot police fired teargas and rubber bullets on Thursday, as demonstrators protested for a second night outside Istanbul City Hall over the shock arrest of the Mayor Ekrem Imamoglu in a graft and terror probe.

The powerful and popular Imamoglu -- who is President Recep Tayyip Erdogan's main political rival -- was detained before dawn on Wednesday, just days before he was to be named as the candidate of his opposition CHP party for the 2028 presidential election.

Imamoglu has urged the nation and the judiciary branch to take a stand against what his party described as a political "coup."

As thousands gathered under tight security on Thursday, a handful of students tried to cross the barriers, prompting scuffles with police who fired rubber bullets, according to an AFP correspondent at the scene.

A second correspondent said police had "used rubber bullets and a lot of tear gas".

It was not immediately clear whether anyone was hurt.

Ozgur Ozel, leader of the main opposition CHP party, warned the police not to provoke demonstrators by firing tear gas or rubber bullets.

"If that happens, the........

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