Labour has called for clarity from the Government over the returnof students to schools and colleges in January.

Shadow education secretary Kate Green and shadow schools minister Wes Streeting have written to Gavin Williamson urging him to provide answers for parents, students and staff about reopening schools after Christmas.

They say questions on the return of students – and evidence about the spread of Covid-19 among young people – must be answered now “not a matter of hours or days” before students are due to return to class.

It came after Boris Johnson said he wanted schools to reopen as planned at the start of January, but he said measures were “under constant review”.

Scientists have suggested that the mutated coronavirus strain could more easily infect children, meanwhile a professor has raised questions about the quality of lateral flow tests which are due to be rolled out in secondary schools.

The Prime Minister has said the Government wants secondary school pupils to return to lessons in a staggered way in the new year if they “possibly can”.

He said the “commonsensical thing to do” was to follow the path of the epidemic.

Labour’s letter to the Education Secretary calls on the Government to publish scientific evidence on the spread of the virus in schools and colleges – and the risk this poses to students, staff and the community.

It demands that the Government puts in place plans to safeguard vulnerable children in the event that schools and colleges close.

Last week, the Government announced that most secondary school and college pupils’ return to class in England would be staggered in the first week of January to help roll out the mass testing of students.

But when asked whether he could guarantee that schools would be back on the planned start dates, Mr Johnson said: “The most useful thing I can tell you at this stage is obviously we want, if we possibly can, to get schools back in a staggered way at the beginning of January in the way that we have set out.”

Ms Green said: “Gavin Williamson’s late announcement on testing has created huge stress and confusion, and now the Prime Minister has said these plans published just five days ago may not happen.

“The Government must provide pupils, parents, and schools with clear information about what will happen in January and what support they will receive.”

On Tuesday, Professor Jon Deeks, of the Institute of Applied Health Research at the University of Birmingham, raised concerns about the quality of lateral flow tests used in universities, which the Government plans to use in schools.

He told BBC Radio 4’s Today programme: “Well we’ll be allowing teachers and students to stay in school who had Covid, we’d be missing people who’ve got Covid.”

Prof Deeks warned that we could “end up with outbreaks” in schools if students are kept in class rather than being told to self-isolate because an asymptomatic test says they are negative.

Home Secretary Priti Patel told Sky News: “Mass testing is up and running across the country as we know and we have been obviously speaking about mass testing in schools and that is something that is under discussion right now across Government for January and when the schools eventually go back.”

On Monday, the National Education Union (NEU) called on the Government to allow schools to move classes online for most pupils for a fortnight at the start of January to allow Covid-19 cases to fall.

A Government spokesman said: “We want all pupils to return in January as school is the best place for their development and mental health, but as the Prime Minister has said, it is right that we follow the path of the pandemic and keep our approach under constant review.

“Our huge expansion of rapid testing will support secondary schools and colleges to stay open to all pupils and reduce the risk of transmission within local communities.”