Thousands of uk students started their academic year under tight restrictions this week as the number of coronavirus cases jumped at universities around the country, with the government refusing to rule out a christmas lockdown.

About 600 students were isolating at the university of glasgow on thursday after 124 cases were confirmed, while 500 students were isolating in halls of residence at dundees abertay university after three cases were confirmed. dozens of cases were also reported at other universities, including in liverpool, manchester and aberdeen.

The jump in cases at universities comes as the number of daily positive coronavirus tests is rising across the uk, topping 6,100 on wednesday, and highlights the challenge of containing outbreaks among hundreds of thousands of students travelling to start their courses.

University officials insist robust measures are in place to keep outbreaks under control, and have urged students to stick to distancing rules. but unions have said tougher action, including a halt to face-to-face teaching, is required.

On thursday, health secretary matt hancock refused to rule out the possibility of stopping students returning home at christmas, a suggestion raised in leaked minutes from a meeting of the governments scientific advisory group for emergencies.

Ive learnt not to rule things out... that includes not spreading between the generations, mr hancock told the bbcs today programme. we just have to work on all contingencies at this stage.

Jo grady, the general secretary of the university college union said threatening to lock students up over the festive period ignored the fact that many staff and students commute to university.

The ucu said universities must take more ambitious steps to protect staff and students, including immediately halting in-person teaching and pausing plans for students to move on to campus.

Any institution that refuses to put the health of its staff, students and local community first is failing its basic civic duty, ms grady said.

The national union of students also rejectedthe suggestion that students should be banned from returning home and said they should not be scapegoatedfor the governments chaotic handling of the crisis.

We must see an urgent investment into digital infrastructure to allow those that want to learn remotely to do so, to eradicate digital poverty and ensure support services, such as mental health services, can be delivered remotely,said larissa kennedy, nus uk president.

The university of liverpool, which has set up a dedicated testing centre for upwards of 70,000 staff and students at the three universities in the city, said a total of 87 cases had been confirmed as of monday.

Louise kenny, executive pro-vice chancellor forthe faculty of health and life sciences, said while any increase in cases was worrying, the number was in line with increases across the city. we are in a city where covid rates are going up in every age bracket, she said.

The university moved lectures and some classes online in response to the rising number of cases in the city, reducing on-campus footfall to 10 per cent of its normal rate, and requires students to take a community pledge to follow local restrictions around large gatherings.

But prof kenny said it was not possible to completely halt practical learning. we cant deliver medical schools or nursing purely online, she said. the counterfactual is we wont be able to graduate the doctors and nurses and midwives that the nhs needs.

Professor gerry mccormac, the convener of universities scotland, which represents the countrys higher education institutions, said new cases were occurring where students have been mixing households in breach of the rules, rather than in the tightly controlled environment of in-person teaching.

We need every member of the university community to adhere to the rules and act in ways that keep themselves and each other safe, he said.