BERKELEY (CBS SF) — Following the cancellation of the Ann Coulter speech at University of California, Berkeley, far-right supporters plan to hold a rally Thursday to denounce what they claim is the attempted silencing of their conservative views, stoking fears of another violent encounter with far-left groups.

UC Police said it was preparing for violence Thursday between militant factions on both sides, even as the speech by the conservative firebrand Coulter was canceled over fears of violence.

THURSDAY MORNING UPDATE: Tensions Mounting Over Threat Of Political Violence In Berkeley

Gavin McInnes, founder of the pro-Trump “Proud Boys,” said he would fly to Berkeley to speak Thursday and was encouraging other alt-right forces to make a large appearance at the gathering, scheduled for 2:00 p.m. at Civic Center Park.

In a YouTube video, McInnes challenged the so-called anti-fascist groups, “… our army will be a bigger audience than most of these liberals get when they do talks. So you f***’ed up. Once again, you have created this mythical universe of Nazis on every corner and you’ve tried to shut it down based on that lie. Well, we’re not allowing that to happen. The show must go on.”

The Proud Boys call themselves Western chauvinists who “refuse to apologize for creating the modern world.” They flooded Berkeley in huge numbers earlier this month and appear to be amassing a return visit from such characters as the “Based Stickman” and others who have made their name with violent responses to the antifa (anti-fascist) anarchists.

Late Wednesday, the City of Berkeley urged peaceful demonstrators in a press release to keep a distance from those violent groups on both sides, and not to get baited by provocateurs.

“This is the best way to keep yourself and others safe. It allows police to focus on and apprehend criminals while keeping bystanders safe,” the statement read. “People with cameras who surround violent incidents can complicate the safety of other peaceful bystanders and impede police. When individuals commit violence surrounded by a peaceful crowd, police are always concerned about how the violence might spill over onto those who are not committing any crime whatsoever.”

The statement also noted, “Separating yourself from violence also prevents those individuals from making their actions the image of your cause.”

There have been an increasing number of violent encounters at UC Berkeley between far-left and far-right groups following the rioting which forced the cancellation of an on campus speech by former Breitbart writer and commentator Milo Yiannopolous in February.

Yiannopolous has vowed to hold a “Free Speech Week” in Berkeley with a series of rallies to protest the school’s handling of right-wing speakers.