The president of Harvard University has resigned after coming under ferocious attack over plagiarism accusations and her response to alleged anti-Semitism on campus amid Israel's brutal war on besieged Gaza.

Claudine Gay, who resigned on Tuesday, is the second Ivy League president to resign in the past month following the congressional testimony — Liz Magill, president of the University of Pennsylvania, resigned on December 9.

Gay was criticised in recent months after reports surfaced alleging that she did not properly cite scholarly sources. The most recent accusations came on Tuesday, published anonymously in a conservative online outlet.

Gay, Magill and Massachusetts Institute of Technology President Sally Kornbluth were engulfed in controversy after the trio declined to give a definitive "yes" or "no" answer to Republican Representative Elise Stefanik's question of whether calling for the genocide of Jews would violate their schools' codes of conduct regarding bullying and harassment, saying they had to balance it against free speech protections.

Gay, who made history as the first Black person to be president of the powerhouse university in Cambridge, Massachusetts, said in her resignation letter that she'd been subjected to personal threats and "racial animus."

Her downfall comes after the university's governing Harvard Corporation had initially backed her after the public relations disaster of the congressional testimony.

'Racist vitriol'

More than 70 lawmakers, including two Democrats, demanded her resignation, while a number of high-profile Harvard alumni and donors also called for her departure.

Still, more than 700 Harvard faculty members had signed a letter supporting Gay, and her job appeared to be safe.

The resignation, first reported by the student-run newspaper the Harvard Crimson, was confirmed shortly after by Gay herself.

"It is with a heavy heart but a deep love for Harvard that I write to share that I will be stepping down as president," Gay said in a statement.

Gay also wrote that she had faced threats to her safety and "racial animus" in the wake of the furore over her handling of claims of mounting anti-Semitism on campus.

The university's governing Harvard Corporation said that Gay had "shown remarkable resilience in the face of deeply personal and sustained attacks."

"While some of this has played out in the public domain, much of it has taken the form of repugnant and, in some cases, racist vitriol directed at her through disgraceful emails and phone calls. We condemn such attacks."

In the United States, the anti-Semitism on campus controversy came amid a rise in attacks and violent rhetoric targeting Jews and Muslims, including at universities, since the start of Israel's brutal war on besieged Gaza.

However, Islamophobic attacks were never taken seriously, like anti-Semitism.

The president of another elite Ivy League institution, the University of Pennsylvania, had already been forced to resign.

Celebration

The House Republican who challenged Gay out during her testimony celebrated the latest academic's downfall.

"TWO DOWN," Representative Stefanik wrote on social media, referring to the resignations of Gay and former University of Pennsylvania president Magill.

"Harvard knows that this long overdue forced resignation of the antisemitic plagiarist president is just the beginning of what will be the greatest scandal of any college or university in history," said Stefanik.

Prime Minister Benjamin Netanyahu of Israel, a close US ally, has claimed that a "whopping wave of anti-Semitism" has "seeped onto university campuses."

Yad Vashem, Israel's official Holocaust memorial, has described it as a "cancer."

Former student and multi-million-dollar donor Bill Ackman claimed in a letter to Harvard's governing boards that "President Gay's failures have led to billions of dollars of cancelled, paused, and withdrawn donations to the university."

Gay, 53, was born in New York to Haitian immigrants and is a professor of political science who, in July, became the first Black president of 368-year-old Harvard.