The government should consider pausing the return of university students with thousands of students already isolating amid Covid outbreaks, Labour has said.
Shadow education secretary Kate Green said the start of term should be delayed while an "effective, efficient testing system" is put in place.
Students have returned to many UK universities, with most having already started term or due to begin on Monday.
The Department for Education said it was working closely with universities.
Ms Green said Labour was concerned about the mental health impacts of students being isolated away from home and said all students should be given the option of remote learning.
She told BBC Breakfast: "We do think it is important that students have a choice. If they feel they are going to be safer at home then they should be able to stay at home and conduct their learning remotely."
Ms Green also asked the government to promise students would be allowed home for Christmas as it would be "unthinkable" that they could be locked in their halls and unable to see families, although she said "public health considerations" should always come first.
But Amanda Milling, Co-Chairman of the Conservative Party said there were "no plans" to keep students at university over Christmas.
"Labour is deliberately creating unnecessary stress for young people to score political points," she said.
About 3,000 students are currently in lockdown at universities from Dundee to Exeter, the Conservative chairman of the Commons education select committee Robert Halfon said.
They include up to 1,700 students at Manchester Metropolitan University - where students say they are being prevented from leaving by security guards and police.
Many students have expressed worry and confusion about the situation, with one saying they had "been left completely in the dark".
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.
In a letter to Education Secretary Gavin Williamson, Ms Green accused the government of failing to prepare for the likelihood that the virus could spread among students and said it was "deeply distressing" students would not get "the university experience they deserve".
The government had "let young people down with the exam fiasco over the summer, and now many of those same students are being let down again", she said.
'We had no warning'
Manchester Met said it had introduced a 14-day self-isolation period at its accommodation at Birley and Cambridge Halls after 127 students tested positive for the virus.
Joe Byrne, a first-year student there, said students had been "left completely in the dark" and "practically locked up against our will".
Another student, Megan Tingey said she was not contacted by the university about the lockdown before police turned up outside her accommodation.
Thousands more students in England are turning up for the new university term this weekend - but the big question is whether they should be heading in the opposite direction and studying from home.
Is it wise or fair for universities to bring students back if they're at increasing risk of being in a Covid outbreak and having to self-isolate?
Accommodation blocks, with shared facilities and filled with young people wanting to socialise, have already seen a wave of outbreaks. So should the brakes be applied to stop this pattern repeating itself?
But after recruiting record numbers of students and promising them a mix of online and face-to-face teaching, it is going to be a very awkward U-turn for universities to switch back to the academic equivalent of working from home.
And would that mean refunds on accommodation and tuition fees?
There are likely to be some chaotic days ahead - and some big decisions to be made about whether to cut numbers on campus. And students must wonder how they've gone from being cooped up at home all summer to now being cooped up in university.
In a statement, to give significant advanced notice due to the requirement to implement the isolation almost immediately".
It said details of how to access food and other provisions had been sent to students.
Hundreds of students are also isolating at Glasgow University because of two coronavirus clusters.
The university said it would offer a four-week rent rebate to all students in university residences in recognition of the "difficult circumstances" under which they were living.
It said those students would also be given £50 each to spend on food and it would invite local mobile food outlets to come to residences.
Across all of Scotland, students have been told not to go to pubs, parties or restaurants over the weekend.
Dr David Duncan, chief operating officer at the University of Glasgow, rejected calls for tuition fees to be refunded and said the university's blended learning courses would be of high quality.
"Most students do want to go to their universities even under the present difficult circumstances, partly for social reasons but also for academic reasons," he said. "It is easier to sustain a difficult academic programme when you have the company of other learners with you."
The government said it was working closely with universities in England to ensure they were well prepared for students to return and would continue to monitor the situation, and public health advice.
Jamie Greene, Scottish Conservatives shadow cabinet secretary for education, called for clarity for students from the Scottish government and said they should be treated "with respect and as adults".
First Minister Nicola Sturgeon has said students were not to blame for outbreaks at universities. "The sooner we get this under control the sooner you will enjoy a normal student life," she said.
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