Students and staff at the Central European University in the Hungarian capital Budapest are protesting against government plans to close it down.
The university says new legislation proposed by the right-wing Fidesz government on Tuesday night makes it impossible for it to function.
It is the focus of a row between Prime Minister Viktor Orban and Hungary-born philanthropist George Soros.
Mr Soros founded the university in 1991 and continues to fund it.
He wanted the CEU to be a bastion of liberal thought and promote the values of an open society and democracy.
But the university appears to have become the latest target in a campaign by Prime Minister Viktor Orban’s government against liberal values.
The government says the CEU and other foreign-funded universities are operating outside the law, and that the new legislation aims to create a new legal footing.
But CEU Rector Michael Ignatieff says the university is fully legal and the new law has been designed to disable it.
“We will defend our achievements vigorously against anyone who seeks to defame our work in the eyes of the Hungarian people,” he said.
The BBC’s Nick Thorpe in Budapest says the new rules would force the CEU to change its name, set up a campus in New York, change its curriculum and become subservient to both the US and Hungarian governments.
Protesting staff and students are now seeking the support of other universities, both in Hungary and worldwide.
It comes at a time of deteriorating relations between US President Donald Trump and Mr Soros, who recently described the new occupant of the White House as “an imposter, a [political] conman and a would-be dictator”.
Relations between Mr Soros and Mr Orban – a keen supporter of the US president – also became strained when Mr Orban accused him of wanting a role in Hungarian politics and supporting the influx of migrants into Europe.
Mr Orban recently claimed Hungary was “under siege” from asylum seekers.
NGOs partially funded by Mr Soros’s Open Society Foundation are already under pressure to close in Hungary.
The Central European University
- Founded to “resuscitate and revive intellectual freedom” in parts of Europe that had endured the “horrific ideologies” of communism and fascism
- Occupies a building that began as an aristocrat’s palace before becoming state-owned offices for a planned socialist economy
- Has nearly 1,800 students, most of whom are Hungarian
- Prime Minister Orban is a former Soros scholarship recipient
- Presents itself as a champion of free speech, with links to universities in Russia, Kyrgyzstan, Georgia and Kazakhstan