Two policemen suffered head injuries after bottles were thrown at them during a nationalist march in Brighton.
The March for England group held its fifth annual event, with counter protests by anti-fascist groups.
About 140 people took part in the march which was temporarily halted twice and re-routed to avoid the seafront.
One of the injured officers was taken to hospital but later discharged. Sussex Police said three people were arrested for public order offences.
Police said the route had been changed “following significant verbal aggression by both groups of demonstrators”.
And mounted police were drafted in to maintain calm as attempts were made to obstruct the march at several points amid “considerable levels of violence”, police said.
Roads were closed in the area, and bus services disrupted.
The march was halted first in Queen’s Road and then in Church Street, where mounted officers were deployed to help with crowd control.