At UC Berkeley, 177 professors and graduate students have signed an open letter urging thousands of colleagues and classmates to boycott campus for four days this month to ensure their “physical and mental safety.”

The strongly worded letter, titled “Boycott the Alt-Right @UCBerkeley,” asks that students, instructors and employees cancel classes, close buildings and “not penalize students who are 

That’s when Milo Yiannopoulos has said he, Steve Bannon, Ann Coulter and other couriers of the far-right agenda are supposed to descend onto campus for four days of rallies and speeches they’re calling “Free Speech Week.”

ALSO: Student group must pay needed fees for 'Free Speech Week,' UC officials say

But as of Sunday, the event remained in doubt after university officials said organizers failed to pay the required fees and rent for the facilities when they turned in a contract for the event late Friday, after missing two earlier deadlines.

The boycott letter, nonetheless, warns that the city of Berkeley will be the site of “explicitly violent alt-right, militia and pro-Fascist events” prompted by the expected arrival of the “odious trifecta,” as one student described the three.

Campus administrators say “Free Speech Week” is no sure thing, because the students who invited the speakers haven’t made the security arrangements needed to reserve rooms for them to speak in. Even so, administrators expect to meet or exceed the extraordinary measures they took Thursday when a far less provocative conservative, Ben Shapiro, spoke at UC Berkeley’s Zellerbach Hall. At an estimated cost of $600,000, the extensive police presence kept hundreds of protesters at bay.

In February, a far smaller police presence failed to protect the campus from masked rioters who smashed windows, set equipment on fire and stopped a scheduled speech by Yiannopoulos.

Now he says he’s coming back with cohorts. And many faculty and students want nothing to do with it.

“As faculty we cannot ask students and staff to choose between risking their physical and mental safety in order to attend class or come to work in an environment of harassment, intimidation, violence, and militarized policing,” says the letter, adding that some students and employees are particularly at risk: “non-white, gender queer, Muslims, disabled, feminists” and others routinely singled out by the right.

Yiannopoulos is a right-wing showman who delights in mocking such groups. Bannon is an ex-adviser to President Trump who edits the right-wing opinion site Breitbart News. And Coulter, an author, has said that “illegal aliens have killed, raped and maimed thousands of Americans.”

The letter also cites the left-right violence that has escalated around the country since Trump became president, including the death of a peaceful protester in Charlottesville, Va., and stabbing deaths in Portland, Ore., and Maryland. Since the inauguration, the East Bay has also seen five violent clashes that have cost taxpayers at least $1.5 million.

“There’s no way UC Berkeley can provide safety and security for four days. This is some sort of fantasy,” said Déborah Blocker, an associate professor of French who signed the letter and intends to teach her two small classes off campus.

But beyond personal safety, Blocker said, “we will do it massively — as a symbol. If they (the right-wing) are going to be handed the keys to this campus ... then academics will go elsewhere.”

Peter Glazer, an associate professor of theater, dance and performance studies who also signed, said the value of boycotting campus is also to “deny the invited speakers the audience, the trouble, and the kind of press they crave.”

UC Berkeley spokesman Dan Mogulof said faculty members are free to decide where and when they teach their classes.

Nanette Asimov is a San Francisco Chronicle staff writer. Email: nasimov@sfchronicle.com Twitter: @NanetteAsimov