University leaders have hit back at plans to force students to be double jabbed before attending lectures.
The move is a "terrible infringement on personal freedom" and would fall foul of contract law, vice-chancellors have warned.
Their intervention comes amid reports that the Government is considering making it compulsory for university students to be fully vaccinated in order to attend lectures or stay in halls of residence.
Boris Johnson is said to have been "raging" about the relatively low vaccine uptake among young people and is determined to apply pressure.
But the suggestion of vaccine passports for lectures has sparked an angry backlash among vice-chancellors, who have questioned the legality of such a move.
"I totally abhor the idea," said Prof James Tooley, the vice-chancellor of Buckingham University. "I find the whole idea totally abhorrent – it is a terrible infringement on personal freedom. This is a step too far in my view. I imagine there will be legal challenges."
Lawyers advising universities have pointed out that, when prospective students accept a place, they enter into a contract with the institution.
If their vaccine status was not originally mentioned as part of this, introducing it as a requirement at a later stage could fall foul of both contact law and consumer law.
Likewise, many students have already entered into contracts with halls of residence and, if no mention of a vaccine passport was made when the contract was signed, it could be problematic to introduce it at a later stage.
The Associate of University Legal Practitioners also pointed to public health legislation which would need to be amended to give the power to make vaccination mandatory.
It said that medical treatment, which includes vaccinations, is currently only mandatory in certain circumstances, and universities cannot make it compulsory unless the law changes.
Nick Hillman, the director of the Higher Education Policy Institute, said such a move may be hard to implement for international students and would risk creating a two-tier system.
"If you come from another country where vaccines haven't been rolled out, you will arrive in the UK and won't have time to be double jabbed in time for the start of term," he said.
Jo Grady, the general secretary of the University and College Union, also criticised the plans, saying: "Sadly, this looks and smells like a Prime Minister trying to pin the blame on students for not yet taking up a vaccine they haven't been prioritised to receive.
"It would be much more useful if the Prime Minister worked with universities and NHS providers to enable and sensitively encourage student vaccination without resorting to compulsion."
Last week, Mr Johnson announced that everyone who wants to go to a nightclub from the end of September will have to show proof of having received two doses of a Covid vaccine.
He also said "other venues where large crowds gather" could be made to adopt the checks, opening the door to their potential use at concerts, theatres and sports matches. Mr Johnson did not rule out requiring them in pubs, stressing that was not his desired outcome but making it clear that it remained an option the Government could adopt.
A Universities UK spokesman said: "Universities are already encouraging students to get vaccinated and not delay, and will continue working with Government and local public health teams to promote uptake over the summer through targeted communications, and by setting up temporary pop-up clinics at convenient locations."