A 57-year-old man was arrested at about 11.45am on Monday in Castle Street in Belfast on suspicion of disorderly behaviour, resisting police and assault on police. He remains in custody.A 23-year-old man was arrested in Donegall Place at 2.45pm on suspicion of common assault on a 32-year-old man. He is in custody too.Meanwhile a 20-year-old man was arrested in the Agincourt Avenue of south Belfast area at 4.15pm on suspicion of disorderly behaviour. He is also still in custody.Police said they received a report of a crowd in the area of Cornmarket in Belfast and a flag protest near Belfast City Hall shortly after 12.15pm on Monday.They said the two groups were kept apart and there were no reports of any disorder.Later, police received a report of a disorderly crowd in Cornmarket shortly after 3.30pm, with some people in the crowd throwing bottles. The crowd dispersed shortly before 4.30pm.