NEW YORK — Hundreds of police officers have raided Columbia University in New York City to disperse pro-Palestinian protesters who earlier took over a building on campus.

Dramatic footage showed police climbing a ladder to enter Hamilton Hall and remove students. Arrests were reported.

The university had earlier told the students to leave or face expulsion.

The demonstrators want the university to divest from Israel over its continuing deadly military operation in the Gaza Strip.

New York Police Department (NYPD) officers were authorized to enter the hall by university authorities after student demonstrators defied a deadline to disperse. One student told the BBC that around 80-100 police had stormed the building.

Columbia said that after the hall was "occupied, vandalized and blockaded, we were left with no choice". In a letter to the NYPD, university president Minouche Shafik wrote that she requested police aid "with the utmost regret".

Officers used flashbang grenades to "disorient protesters" as the raid commenced, the BBC's US partner CBS News reported.

Some students alleged that police clad in riot gear manhandled demonstrators as they stormed the building, with one telling the BBC that three people had been pushed down the stairs by NYPD officers. The interview was cut short moments later after an officer interrupted and slammed shut a window through which the conversation had been happening.

NYPD assistant commissioner of public information, Carlos Nieves, defended the officers. He said that students had "barricaded" the doors to Hamilton Hall with "conference tables, chairs or soda machines". He alleged they had also blocked windows with newspaper so officers "couldn't see".

CBS reported that there were about 50 arrests.

The BBC's Nomia Iqbal, reporting from Columbia University, reported that several NYPD buses were seen leaving the scene, likely filled with protesters.

Huge cheers of support by anti-war crowds were heard as the arrested students were marched off with their hands in zip ties, she added. People chanted: "Let them go!"

The NYPD later said the building was cleared and no injuries were reported.

The activists have been occupying a tent camp at the Ivy League school in upper Manhattan for nearly two weeks.

US universities have been gripped by protests as students demand a boycott of companies and individuals with ties to Israel during the war in Gaza.

Elsewhere, police also raided City College of New York in Harlem on Tuesday night, US media said, with dozens of arrests reported at the campus.

On campuses in Texas, California, Georgia, North Carolina, Utah, Virginia, New Mexico, California, New Jersey, Connecticut and Louisiana, police have arrested more than 1,000 protesters.

On the west coast, lengthy clashes broke out between pro-Israel and pro-Palestinian demonstrators at the University of California in Los Angeles, after school administrators moved to shut down an encampment it called "unlawful".

Counter-demonstrators clad in black arrived at the campus at around midnight local time, before trying to tear down barricades around the encampment, the LA Times reported. Video footage showed flares and fireworks being set off, while other clips showed scuffles between the groups.

Some authorities have been negotiating with student activists while others have issued ultimatums that have led to police being called in.

National politicians have called on colleges to do more, highlighting reports of antisemitism at some of the demonstrations.

President Joe Biden earlier said demonstrations should be peaceful, but "forcibly taking over buildings is not peaceful - it is wrong".

His Democratic colleague, New York Congresswoman Alexandria Ocasio-Cortez, condemned the police response at Columbia and urged Mayor Eric Adams to find a "de-escalatory path".

"This is the opposite of leadership and endangers public safety," she wrote. "A nightmare in the making. I urge the mayor to reverse course."

Another New York Democrat, Congressman Jamaal Bowman, attacked what he called "the militarisation of college campuses" by police. — BBC