WASHINGTON, April 25, 2024 (BSS/AFP) - President Joe Biden supports freedom of expression on US campuses, the White House said Wednesday, as more and more university students protest Israel's war in Gaza.

Ongoing protests at New York's Columbia University have sparked intense attention from media and politicians -- and similar demonstrations across the country.

Protesters say they are expressing solidarity with Palestinians in Gaza, where the death toll has topped 34,200, according to the Hamas government's Ministry of Health.

But pro-Israel supporters and others worried about campus safety have pointed to anti-Semitic incidents, and argued that campuses are encouraging intimidation and hate speech.

"The president believes that free speech, debate and nondiscrimination on college campuses are important," White House press secretary Karine Jean-Pierre told a briefing.

"We believe in people being able to express themselves in a peaceful manner. But when we're talking about hateful rhetoric, when we're talking about violence, we have to call it out."

Biden on Sunday denounced "blatant anti-Semitism" that has "no place on college campuses."

At Columbia, meanwhile, Republican speaker of the House Mike Johnson decried "the virus of anti-Semitism," calling for the university's president to resign.

"If this is not contained quickly, and if these threats and intimidation are not stopped, there is an appropriate time for the National Guard," Johnson said.

In a high-profile incident in 1970, the National Guard at Kent State University in Ohio fired on students during anti-Vietnam War protests, killing four.

As pro-Palestinian protests have spread, hundreds of demonstrators at the University of Texas were in a tense standoff with mounted state troopers, while elsewhere on campus police in riot gear were pushing back protesters, according to videos on social media.

Amid growing anger at the death toll in Gaza -- especially among younger Americans -- Washington has tried to walk a tightrope on supporting Israel as Biden runs for reelection in November.

The White House demanded "answers" Wednesday from Israeli authorities after mass graves were discovered in Gaza -- while President Joe Biden the same day also approved billions in military aid to its key Middle Eastern ally.

Israel launched the war in Gaza after an unprecedented Hamas attack on October 7 that resulted in the deaths of around 1,170 people, according to an AFP tally of Israeli official figures.