Dozens of protesters took over a building at Columbia University in New York early on Tuesday, barricading the entrances and unfurling a Palestinian flag out of a window in the latest escalation of demonstrations against the Israel-Hamas war that have spread to US college campuses nationwide.

Video footage showed protesters on Columbia's Manhattan campus locking arms in front of Hamilton Hall and carrying furniture and metal barricades to the building, one of several that was occupied during a 1968 civil rights and anti-Vietnam War protest on the campus.

Posts on an Instagram page for protest organisers shortly after midnight urged people to protect the encampment and join them at Hamilton Hall.

The student radio station, WKCR-FM, broadcast a play-by-play of the hall’s takeover, which occurred nearly 12 hours after Monday’s 2pm deadline for the protesters to leave an encampment of around 120 tents or face suspension.

Representatives for the university did not immediately respond to emails requesting comment on Tuesday.

Universities across the US are grappling with how to clear out encampments as commencement ceremonies approach, with some continuing negotiations and others turning to force and ultimatums that have resulted in clashes with police. Dozens of people were arrested on Monday during protests at universities in Texas, Utah and Virginia, while Columbia said hours before the takeover of Hamilton Hall that it had started suspending students.

Demonstrators are sparring over the Israel-Hamas war and its mounting death toll, and the number of arrests at campuses nationwide is approaching 1,000 as the final days of class wrap up. The outcry is forcing colleges to reckon with their financial ties to Israel, as well as their support for free speech. Some Jewish students say the protests have veered into anti-semitism and made them afraid to set foot on campus.

On Monday, student activists at Columbia defied the 2pm deadline to leave the encampment. Instead, hundreds of protesters remained. A handful of counter-demonstrators waved Israeli flags, and one held a sign reading, “Where are the anti-Hamas chants?”

While the university didn’t call police to roust the demonstrators, school spokesperson Ben Chang said suspensions had started but could provide few details.

Protest organisers said they were not aware of any suspensions as of Monday evening.

Columbia’s handling of the demonstrations also has prompted federal complaints.

A class-action lawsuit on behalf of Jewish students alleges a breach of contract by Columbia, claiming the university failed to maintain a safe learning environment, despite policies and promises. It also challenges the move away from in-person classes and seeks quick court action requiring Columbia to provide security for the students.

Meanwhile, a legal group representing pro-Palestinian students is urging the US Department of Education’s civil rights office to investigate Columbia’s compliance with the Civil Rights Act of 1964 for how they have been treated. (AP)