Washington DC - The White House insisted Sunday that pro-Palestinian protests that have rocked US universities in recent weeks must remain peaceful after police arrested around 275 people on four separate campuses over the weekend.

"We certainly respect the right of peaceful protests," National Security Council spokesman John Kirby told ABC's This Week.

But, he added, "We absolutely condemn the antisemitism language that we've heard of late and certainly condemn all the hate speech and the threats of violence out there."

The wave of demonstrations began at Columbia University in New York, but they have since spread rapidly across the country.

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While peace has prevailed in many campuses, the number of protesters detained – at times by police in riot gear using chemical irritants and tasers – is rising fast.

They include 100 at Northeastern University in Boston, 80 at Washington University in St. Louis, 72 at Arizona State University, and 23 at Indiana University.

Among those arrested at Washington University was Green Party presidential candidate Jill Stein, who faulted police for aggressive tactics she said provoked the sort of trouble they are meant to quell.

"This is about freedom of speech... on a very critical issue," she told CNN shortly before her arrest Saturday. "And there they are, sending in the riot police and basically creating a riot."

College administrators have struggled to find the best response, caught between the need to respect free-speech rights and the imperative of containing inflammatory and sometimes violently antisemitic calls by protesters.

At the University of Southern California, school officials late Saturday closed the main campus to the public after pro-Palestinian groups again set up an encampment that had been cleared earlier, the school announced on X.

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With final exams coming in the next few weeks, some campuses – including the Humboldt campus of California State Polytechnic University, have closed and instructed students to complete their classes online.

The activists behind the campus protests – not all of them students – are calling for a ceasefire in Israel's war with Hamas and want colleges to sever ties with Israel.

Israel's retaliatory offensive has killed at least 34,454 people in Gaza, mostly women and children.