A group of Oxford dons have called for the university’s harassment policies and social media guidelines to be changed due to fears they inhibit freedom of speech.

They said the university’s policies on harassment and social media use prohibit “speech that is lawful” and are therefore in breach of the university’s legal duty to protect freedom of speech.

“These policies frustrate academic freedom – the lifeblood of this university – and harm academic careers,” the dons said.

The changes were called for in a question tabled to Oxford’s sovereign body Congregation by Michael Biggs, professor of sociology, and Roger Teichmann, tutor and fellow in philosophy, which was signed by seven others, including Nigel Biggar, professor of pastoral theology.

It comes after Oxford academic Abhijit Sarkar said he was subjected to threats of rape and murder online after being accused of “Hinduphobia” when he criticised Rashmi Samant, the first female Indian student to lead the Oxford University Students’ Union.

Dr Sarkar linked Ms Samant and her family to far-right Hindu nationalism on Instagram, and his post was reported to the police and investigated, although no further action was taken.

The Times Higher Education website reported that Ms Samant resigned from her position soon after being elected and said she had been targeted for her religion and bullied because of the allegations made. Her complaint that Dr Sarkar had harassed her was upheld by the university.

The academics said that the current policies were “unlawful” and did not comply with the university’s duty to safeguard academic freedom.

They criticised social media guidelines that state staff must treat one another with “professionalism” and “courtesy”, stating: “The requirement that academic staff so conduct themselves is reasonable but legally baseless – speech that lacks respect, professionalism, etc, is still free speech within the law.”

They added that “as a matter of principle, the [social media] policy of the university – as an institution founded on tolerance, free thought and free expression – should in all circumstances be more liberal and open-minded than the policy of social media platforms”.

The dons said that failure to safeguard academic freedom “poses a grave risk to the university’s reputation”.

In a statement, the university said: “The university is both allowed and obliged to take action in response to concerns about the treatment of a member of the university community by a fellow member of the same community and the university is confident that its policy and procedure on harassment and its social media guidance reflect and comply with its legal obligations.”