Free speech is under growing threat at Queen's University, Belfast, a report has claimed.
The institution has some of the most severe restrictions in the UK, according to a survey of more than 100 campuses.
QUB was one of 63 universities graded 'red', indicating it has "banned and actively censored ideas on campus".
Its attitude to free speech has worsened in the last year, the survey by online magazine Spiked suggested. It used Freedom of Information requests and policy analysis to assess the level of intolerance at universities.
Using a traffic light ratings system, 55% of 115 universities examined were deemed "red", compared to 41% last year.
Queen's was among 20 institutions added to the red list since last year. Ulster University was classified amber, meaning it has "chilled free speech through intervention".
QUB has been at the centre of three high-profile controversies in recent times. Last year it was criticised after cancelling a conference discussing the fallout from the Charlie Hebdo massacre.
Twelve people died when two brothers, Said and Cherif Kouachi, fired on journalists at the satirical magazine's offices in Paris.
Vice-chancellor Patrick Johnston cited concerns about the university's reputation and the security risk to delegates. He later reversed his decision after a risk assessment, and the conference went ahead in June.
In November 2013 the chart-topping hit Blurred Lines by Robin Thicke became the first song to be banned in the history of Queen's Students' Union. The controversial song was accused of being misogynistic and promoting rape culture.
The student representative council voted 26-22 to join more than 20 other student unions across the UK in banning it. And in March 2013, Queen's Students' Union clamped down on a pro-life society over material it handed out.
Explaining the ranking, Spiked said: "Queen's University Belfast and Queen's University Belfast Students' Union collectively create a hostile environment for free speech.
"The university, which has moved to a red ranking, effectively bans racist, sexist and sectarian speech. The students' union, which has also moved to a red ranking, similarly bans racist, sexist and sectarian speech.
"It has also banned Blurred Lines and clamped down on a pro-life society. The institution's overall ranking moves to red."
Free speech advocate Padraig Reidy said: "Universities have a duty to promote debate and discussion. The decision by QUB vice-chancellor Patrick Johnston to cancel a symposium on Charlie Hebdo and free speech last year set a terrible example to students who should be encouraged to tackle big, provocative ideas."
Tom Slater from Spiked said the free expression issue is "bleaker than anyone could have imagined".
Queen's University and Queen's Students' Union both declined to comment. The survey suggests student unions are more likely to censor speech or ideas than the universities themselves.
It comes as the "Rhodes Must Fall" campaign continues to escalate at Oxford University.
The campaign is calling for the removal of the memorial to Cecil Rhodes, the controversial British imperialist, at Oriel College.
It led Oxford University's chancellor Lord Patten to criticise students for challenging its "freedom of debate".
According to Spiked, institutions introduced 148 bans in the last three years, with 30 banning newspapers, 25 banning songs, 20 banning sports clubs or societies and 19 banning speakers or events.
The students' union at the University of East Anglia banned The Sun, sombreros and the hockey team after it played a game of "gay chicken". And Swansea University students banned a pole fitness society for being "inextricably linked to the sex industry".