SACRAMENTO, California — The ongoing strike at the University of California further expanded to two more campuses on Monday, with thousands of academic workers demanding action for those facing criminal and discipline charges related to pro-Palestinian protests.

UC San Diego and UC Santa Barbara were officially on strike, announced the workers' union United Auto Workers Local 4811 in social media posts on Monday.

Holding signs such as "UAW on Strike" and "Unfair labor practice "while chanting slogans protesting the University of California's treatment of pro-Palestinian protesters, union members marched on the UC San Diego campus and rallied before the library, where several tents were set up to facilitate the strike, according to videos and photos posted online by local TV stations and the union.

In a statement on Monday, UC San Diego reiterated the UC system's stance that called the strike "illegal" as it violated the union's contract with the UC, in which both sides agree on "no strike" over non-labor issues.

"This illegal strike hurts our students by disrupting typical class delivery, assignment grading and other learning activities during a critical time of year when students are diligently preparing for finals and completing final projects," the university said in the statement.

The union's members voted last month to authorize a strike to protest the university's controversial response to pro-Palestinian demonstrations on campus, which they said has caused unsafe work conditions and violated their free speech rights.

The first UC campus that stood up and withheld labor was UC Santa Cruz, where academic workers walked off the job on May 20. The walkout then spread to UC Los Angeles and UC Davis on May 28.

UC Irvine plans to join the strike on Wednesday. By then, the total number of strikers is expected to reach 31,500 at six of the UC system's 10 campuses, according to the union.

Meanwhile, police arrested dozens of pro-Palestinian demonstrators on Monday for trespassing after they occupied the lobby of a San Francisco building that houses the Israeli consulate.

Police zip-tied the hands of protesters, put them in police vans, and drove them away.

Officers arrested 69 people who refused to vacate the building, cited them, and released them from San Francisco County Jail, the San Francisco Police Department said in a statement. Another demonstrator was cited and released at the scene for the same charge, it said.

Demonstrators entered the building and occupied the lobby for several hours. The protesters posted signs on the front doors calling for an end to the conflict.