US universities have been emailing international students and staff advising them to return to campus before President-elect Donald Trump takes office in January, amid concerns over his plans for mass deportations.

"All international students are worried right now," University of Colorado Denver professor Chloe East told the BBC.

Trump, a Republican, has pledged to enact the largest deportation operation in history and use the US military to help.

More than 400,000 undocumented students are enrolled in US higher education, according to the Higher Ed Immigration Portal.

Officials in Trump's incoming administration have suggested they will build vast holding facilities for undocumented immigrants on the deportation list.

His incoming border tsar Tom Homan has said violent criminals and national security threats will take priority for removal from the country. But that has not allayed concerns in higher education.

"Students are incredibly overwhelmed and stressed out right now as a result of the uncertainty around immigration," Prof East told the BBC.

"A lot of students have concerns about their visas and whether they'll be allowed to continue their education."

In November, the University of Massachusetts issued a travel advisory to its international students and faculty, encouraging them to "strongly consider" returning to campus from winter break before Trump takes office on 20 January.

"Based on previous experience with travel bans that were enacted in the first Trump Administration in 2016, the Office of Global Affairs is making this advisory out of an abundance of caution," the college said.

Trump signed an executive order during his first week in the White House in 2017 banning nationals of several predominantly Muslim nations, as well as North Korea and Venezuela, from visiting the US. During his first presidency, he also proposed some limitations on student visas.

The Massachusetts Institute of Technology and Wesleyan University have also issued travel advisories, urging students and staff to return to the US before inauguration day.

At Yale University, the Office of International Students and Scholars hosted a webinar this month fielding concerns from students about potential immigration policy shifts, the student newspaper reported.

This includes foreign-born students who are protected by the Deferred Action for Childhood Arrivals (DACA) policy.

Trump has attempted to end the Obama-era programme, which shielded over half a million migrants who came to the US as children from deportation.

Prof East said students from Asia, particularly China, are feeling "uncertainty" about US-China relations under Trump.

Aoi Maeda, an international student from Japan studying at Earlham College in Indiana, is among those with concerns about her academic future.

"I am planning to graduate in May 2026, but now that the administration is going to be a little bit more dangerous, I'm less hopeful about things going well," she said.

"[Trump] claims that he is only interested in keeping illegal immigrants out of the country, but he also kind of tries to move the goal post a lot of times," Maeda continued.

"I feel like us international students with a visa might get affected, and it'll become easier to deport us."