Shadow education secretary Kate Green said autumn term, due to start tomorrow for many, should be delayed where it has not already begun.
At least 32 universities have been hit with outbreaks over the past fortnight, with more than 500 cases recorded and up to 4,000 students currently in self-isolation.
Some 1,700 students at Manchester Metropolitan University are in lockdown and barred from leaving by the police and security guards after 127 cases were recorded. Hundreds of thousands at Scottish universities were banned from socialising this weekend.
Labour cited the “unthinkable” mental health impact of a potential Christmas lockdown on campuses, separating families. The idea was suggested by Sage, the Government scientific advisory group, this week and a second Government minister has refused to rule out.
In a letter to Education Secretary Gavin Williamson, Ms Green wrote: "Universities have done all they can to prepare for students’ safe return, but the government have again let young people down.
“It is unthinkable that students will be locked in their rooms and unable to return home to spend Christmas with their families.
"The Government must promise that this will not happen, and work with universities to enable every student to access tests so that they can travel home safely.
“The government should also consider a delay to the start of term or a pause in migration for universities where term has not yet begun to allow improvements in testing capacity and remote learning provision."
Culture Secretary Oliver Dowden said on Sunday morning that students “should” be able to return to family homes in December “if we all pull together and observe these new rules, we follow the guidance”.
But Amanda Milling, co-chair of the Conservatives, said there were "no plans" for a Christmas lockdown. Downing Street declined to comment.
Robert Halfon, chair of the powerful Commons education select committee, joined the leading Oxford medicine professor Carl Heneghan in calling for tuition fees to be waived this year, with most teaching being delivered online.
At least ten more universities have shifted to entirely online learning over the past fortnight as union leaders ramp up pressure on bosses to ditch the current “blended” formula of virtual lectures and face-to-face classes.
Some students are trying to break free from accommodation contracts so they can flee campus for the year, despite the Government ordering them to stay to avoid spreading the virus back home.
They say they are “terrified”, “locked up” and banned from leaving for exercise, taking rubbish out or visiting supermarkets.
Prof Mark Woolhouse, professor of infectious disease epidemiology at the University of Edinburgh, said the situation was "entirely predictable".
"Students didn't start this current phase of the epidemic, this began way back in August, and the students just got caught up in it," he said.
Labour accused the Government of failing to prepare for outbreaks that its own scientific advisors had warned highly likely, and said it was "deeply distressing" students would not get "the university experience they deserve".
The Government has "let young people down with the exam fiasco over the summer, and now many of those same students are being let down again" the party said.
A Department for Education spokeswoman said: "Students should follow the latest health advice - just like the wider public. They should stay at university in the event that they have symptoms, have to isolate, there are additional restrictions imposed locally, or there is an outbreak on campus or in their accommodation."