At least 47 people were arrested at Yale University on Monday during pro-Palestinian protests, and new demonstrations broke out at other US campuses over Israel's war in Gaza amid growing concerns about the safety of Jewish students.

Pro-Palestinian demonstrators have set up encampments at the University of Michigan and at universities in the Boston area, Sunday night, including at the Massachusetts Institute of Technology (MIT) in Cambridge, Emerson College in Boston and Tufts University in Medford. Harvard University closed Harvard Yard until Friday in apparent anticipation of demonstrations.

Passover, a major Jewish holiday, started at sundown Monday night, and some groups have expressed fears for the security of Jewish students who will be celebrating.

President Joe Biden on Monday condemned antisemitic protests on college campuses and decried "those who don't understand what's going on with the Palestinians", he said, without expanding on what he meant.

As the New York Police Department built up a large presence around Columbia University on Monday, New York Governor Kathy Hochul visited the campus to address security concerns.

"Students are scared," Hochul said in a video posted on X. "They are afraid to walk on campus. They don't deserve that."

School administrators have tried to defuse the protests while balancing the free speech rights of protesters and the fears of many Jewish students, who said some of the demonstrations have veered into antisemitism.

At Columbia, where police last week arrested more than 100 pro-Palestinian demonstrators who had set up an encampment, the university canceled in-person classes on Monday.

The scene at Columbia University's growing encampment appeared quiet Monday morning. There were about 70 green, blue and yellow tents on the lawn in front of the school library.

Early Monday, University President Nemat Shafik said that school leaders would be coming together to discuss a way to bring an end to "this crisis".

In a statement to the university community, Shafik said: "The decibel of our disagreements has only increased in recent days. These tensions have been exploited and amplified by individuals who are not affiliated with Columbia who have come to campus to pursue their own agendas."

US Representative Elise Stefanik, a New York Republican who questioned Shafik at a congressional hearing last week about antisemitism on the campus, wrote her a letter calling on her to resign, saying that "anarchy has engulfed the campus''.

New England Patriots football team owner Robert Kraft, a Columbia alum whose name is on the Jewish student center he helped to fund, released a statement Monday saying he no longer supports the university.

"I am no longer confident that Columbia can protect its students and staff and I am not comfortable supporting the university until corrective action is taken," Kraft posted on social media.

At Yale in New Haven, Connecticut, several dozen protesters were arrested Monday morning after officials said they defied warnings to leave an encampment at Beinecke Plaza on campus Friday night.

At the center of the University of Michigan's campus in Ann Arbor, more than 100 pro-Palestinian students have camped out in tents.

A group of about a dozen students holding Israeli flags stood nearby. A few police officers kept watch but didn't engage with the demonstrators.

An announcement of the closure, posted to yard entrance gates, warned of disciplinary measures against Harvard students and affiliates who bring in unauthorized structures such as tents or tables or block access to building entrances.

More than 1,500 Yale alumni, students and parents have signed a letter in support of the demonstrations there. The letter said that donations to the university should be withheld until the administration publicly commits to divest from companies that are helping to supply weapons to Israel.

The New York University Palestine Solidarity Coalition, a group of New York University organizations, have organized an encampment of tents in a circle formation in front of the Stern School of Business. The encampment has been surrounded by metal barricades, and NYU campus security officers are controlling entry and exit from the grounds.