Turkish protesters clash with police over Istanbul mayor's detention

Turkish police have fired tear gas and water cannon at protesters in Istanbul.
They have been demonstrating for a fourth night, over the detention of the city's Mayor.
Crowds of several thousand people continue to defy government orders banning protests.
Ekrem Imamoglu has been transferred to a courthouse, on allegations of corruption, bribery and terrorism. Prosecutors have called for his formal arrest.
Imamoglu's supporters say his detention is politically motivated. The Turkish interior ministry says 323 protesters were arrested in Istanbul on Saturday night.
Thousands more have joined protests in the Turkish capital Ankara.