Far-right racist thugs marred BlackLivesMatter demonstrations in London on Saturday leading to the arrest of more than 100 people.
Police were attacked by demonstrators, some of whom were far-right activists, after thousands gathered saying they were protecting statues.
PM Boris Johnson said: “Racist thuggery has no place on our streets.”
An investigation is also under way after a man was seen urinating next to a memorial of PC Keith Palmer, who was killed in the 2017 Westminster attack.
Separately on Saturday, a number of peaceful anti-racism protests were held in London and around the country.