A US judge has issued a temporary restraining order blocking the Trump administration from enforcing a ban the president ordered barring Harvard University from accepting international students.

The order by Judge Allison Burroughs, who is based in Massachusetts, said the oldest university in the US would face "immediate and irreparable injury" if the proclamation went into effect.

It comes in response to a lawsuit filed by Harvard on Thursday accusing President Donald Trump of waging a "government vendetta" intended to stifle free speech.

Trump has argued that the ban is necessary on national security grounds, and has accused Harvard of not doing enough to stop antisemitism on campus.

The federal judge's order comes only hours after Harvard amended an existing lawsuit against the US government, claiming that Trump's move is "part of a concerted and escalating campaign of retaliation by the government in clear retribution for Harvard's exercising its First Amendment rights" to free speech.

Harvard President Alan Garber also issued a statement saying that the Ivy League school was developing contingency plans for international students in the event they are not able to travel to campus.

The world's wealthiest university has been embroiled in a legal battle with the Trump administration after it froze billions of dollars of federal funding and accused the institution of failing to root out antisemitism on campus.

In May, Department of Homeland Security Secretary Kristi Noem revoked certification Harvard needed to enrol foreign students on campus, a move that was swiftly blocked by a judge.

The BBC has contacted the DHS for comment on the latest order.

Another federal judge upheld that decision last week, saying she would issue a longer-term hold that would allow international students to continue their studies at Harvard while the legal battle plays out.

The move triggered Trump's order on Wednesday, which suspended for an initial six months the entry of foreign students seeking to study or participate in exchange programmes at Harvard University.

Trump's proclamation accused Harvard of developing "extensive entanglements" with foreign countries and continuing to "flout the civil rights of its students and faculty".

For the 2024-2025 school year, Harvard enrolled nearly 7,000 foreign students, who made up 27% of its population.