Staff at the University of Oxford have been warned they may be displaying racist behaviour if they fail to look another student in the eye or talk to them directly in conversation.

Scholars have also been told to cut out casual racism, for instance asking a black or ethnic minority student where they are “originally” from or joking about a foreign-sounding accent.

The warning comes as part of an anti-racism briefing circulated by the institution’s equality and diversity unit the new term newsletter.

Officials highlight that such “micro-aggressions” are inappropriate and can lead to mental ill health in some students, but critics have called the instructions patronising and claim they are in violation of free speech.

“Sometimes called ‘micro-aggressions’, subtle everyday racism can appear trivial,” the newsletter said. “But repeated micro-aggressions can be tiring and alienating (and can lead to mental ill health).

“Racial micro-aggressions might include not making eye contact or speaking directly to people; not believing someone is British (‘Where are you from? No, I mean originally . . .’); ‘jokes’ drawing attention to someone’s difference, their accent or nationality.”

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The newsletter said that it was working to address the issue by raising awareness “of this type of subtle racism” in its training for people working within the university.

“Some people who do these things may be entirely well-meaning and would be mortified to realise that they had caused offence,” it said. “But this is of little consequence if a possible effect of their words or actions is to suggest to people that they may fulfil a negative stereotype, or do not belong.”

Tom Slater, co-ordinator of The Free Speech University Ranking (FSUR) project that highlights censorship on university campuses, said it was ridiculous to suggest that not looking someone in the eye was a form of racism, however.

“This is all part of a chilling desire on the part of university authorities to police not just opinions, but everyday conversations between students,” he told The Times.

“It’s not only deeply authoritarian, it has a chilling effect on how students interact with one another.

A report from the FSUR group last year named Oxford University as one of the most restrictive in the country for free speech.