More than 70 people were arrested during clashes between right-wing and anti-fascist protesters which brought a town centre to a standstill.
Police condemned the violence in Bolton, Lancashire, which erupted between supporters of controversial right-wing group The English Defence League (EDL) and Unite Against Fascism (UAF).
Thousands of people took part in a rally in Victoria Square, with at least two police officers and members of the public injured. At least 74 arrests were made, more than 55 from the UAF and nine from the EDL, police said.
Officers said UAF protesters were responsible for most of the trouble - and the organisation's joint secretary, Weyman Bennett, said he was arrested and charged with conspiracy to organise violent disorder.
He hit out at the policing, insisting he was grabbed by officers while protesting peacefully.
"I have been to more than 200 demos and never been arrested," he said. "Officers came up to me as soon as I arrived and said they would arrest me. They are hostile to anti-racists and there needs to be an investigation. Police neutrality needs to be questioned."
Assistant Chief Constable Garry Shewan, from Greater Manchester Police, who led the policing operation, said his officers faced "a lot of hostility" and "unwarranted attacks", resulting in injuries.
He said the EDL had protested by flag-waving and "vitriolic name-calling" but he reserved his criticism for the UAF.
"We have seen groups of people, predominantly associated with the UAF, engaging in violent confrontation," the officer said. "It is clear to me that a large number have attended with the sole intention of committing disorder and their actions have been wholly unacceptable. Turning their anger on to police officers, they acted with, at times, extreme violence and their actions led to injuries to police officers, protesters and members of the public."
At the peak of the protest there were 2,000 EDL protesters in the square, and around 1,500 from UAF, police said.