Huge crowds gathered outside Istanbul City Hall late Saturday for a fourth night of protests over the arrest of Mayor Ekrem Imamoglu, who has blasted official allegations against him as "immoral and baseless".

The demonstrations, which began in Istanbul on Wednesday, have since spread to more than 55 of Turkey's 81 provinces, sparking clashes with riot police in the country's worst street protests in more than a decade.

Imamoglu's arrest -- for "terrorism" and "corruption" -- came just days before he was to have been formally named as the main opposition CHP's candidate in the 2028 presidential race.

"Dictators are cowards!" and "AKP (Turkey's ruling party), you will not silence us!" read some of the placards in the Istanbul protest Saturday night, which appeared bigger and denser than the previous night.

Officers charged the City Hall gathering shortly after midnight (2100 GMT) using tear gas and forcing those who could to take refuge in the City Hall building.

Many were arrested, according to AFP journalists, but no official data was immediately........

© International Business Times