MPs and human rights groups have criticised the Metropolitan Police after 52 people were arrested in London on the day of the Coronation.
EDnews informs via BBC that among those held was the head of the group Republic, which wants to scrap the monarchy and elect a head of state.
Graham Smith, who was released on Saturday evening after 16 hours in custody, said there was "no longer a right to peaceful protest in the UK".
Scotland Yard said it had acted "in a proportionate manner".
Commander Karen Findlay defended her officers' response to protests during the day of the Coronation, saying they had a duty to intervene "when protest becomes criminal and may cause serious disruption".
She added that the Coronation was a "once in a generation event and that is a key consideration in our assessment".
Hundreds of protesters gathered in the rain in central London on Saturday, with chants including "down with the Crown", "don't talk to the police" and "get a real job".
Other protests were organised in Cardiff, Glasgow and Edinburgh. No arrests were reported outside London.