A major security operation is underway to prevent more violence breaking out in Belfast.

Last night loyalists clashed with police over Belfast City Council's decision to restrict the flying of the union flag over Belfast City Hall.

Eight police officers were injured as rioters threw petrol bombs. 

Twelve people have been arrested including a 13-year-old boy. 

Protesters are expected to stage another demonstration in Belfast later today. 

Ulster Unionist party leader Mike Nesbitt says it should be called off.