Reopening schools in September is an "absolute priority" for the government and it will be safe, Housing Secretary Robert Jenrick has said.
It comes after teaching unions called for clarity amid a rise in the number of coronavirus cases and the decision to pause lockdown easing in England.
"We have to get children back to school in September," said Mr Jenrick.
Schools are due to open in England, Scotland, Wales and Northern Ireland to all pupils at the start of next term.
They closed in March, except to the children of key workers, but some reopened to certain year groups before the summer holiday.
However, unions have raised questions over the plans to reopen schools, after England's chief medical officer Prof Chris Whitty warned the country is "near the limit" for opening up society.
And earlier this weekend, two scientists advising the government said there may need to be trade-offs around lockdown easing - for example some restrictions may need to come back into force to allow pupils back into the classroom.
Asked about the issue by the BBC, Mr Jenrick said it was "so important" that children have face-to-face contact with their teachers.
"We're working very closely with headteachers and the teaching unions to make sure that all the steps necessary are put in place over the summer so that the children can go back in September and it is an absolute priority for the government," he said.
Mr Jenrick said he believes that schools "will be safe in September".
"We published very detailed guidelines and of course we're going to keep working with headteachers over the course of August as they finalise their own plans as to how their schools can operate safely in accordance with the guidelines."
Mr Jenrick added that parents know that remote learning "isn't a substitute for getting children back into the classroom".
On Sunday, Patrick Roach, the general secretary of the NASUWT teachers' union, told the Observer ministers will have to convince staff and parents that it is still safe to reopen schools next month.
"The warning from the chief medical officer that a fine balance has to be struck in ensuring public health at this stage of the pandemic, and that the country may have reached the limits to the easing of lockdown, will no doubt prompt questions for many parents as well as for those working in schools," he said.
Mr Roach warned that, if schools are to reopen safely, the government needed to give teachers clarification around the latest scientific advice "as well as sufficient time to review and, if necessary, adjust their reopening plans".
The National Education Union also issued a statement, saying the government needs "to monitor the situation nationally and in each region" and "be transparent about what the picture means for schools".
"It is clear, however, that [the] government needs a plan B in the event that restrictions have to be increased in or before September," said the union's deputy general secretary Avis Gilmore.
Boris Johnson has previously pledged that both primary and secondary schools in England will return in September "with full attendance".
The school term in Northern Ireland and Wales also begins in September, but in Scotland the autumn term begins in August.
Prof Graham Medley, chairman of the Scientific Advisory Group for Emergencies (Sage) sub-group on pandemic modelling, said that pubs or "other activities" in England may need to close to allow schools to reopen next month.
"It might come down to a question of which do you trade-off against each other, and then that's a matter of prioritising. Do we think pubs are more important than schools?"
Prof Calum Semple, who also advises the government, said there would need to be "some hard decisions" about which restrictions may need to be reintroduced, adding: "Whether that's potentially the pubs and the hospitality sector taking a hit in preference to education will be a political decision."
A Department for Education spokesman said: "We have set out the controls schools should use, including cleaning and hygiene measures, to substantially reduce the risk of transmission of the virus when they open to all children from September."
Mr Jenrick also dismissed newspaper reports that there were plans to introduce shielding for people above a certain age as "speculation".
"You would expect the government to be considering all of the range of options that might be available," he told Times Radio. "That's not something that is being actively considered."
On Friday, the PM announced further easing of the lockdown would be delayed.
Measures due to come in this weekend, including the reopening of casinos, bowling alleys, skating rinks and some close-contact services, as well as the return of indoor performances and pilots of large gatherings in sports venues and conference centres, have been postponed for at least a fortnight.
Mr Johnson said on Friday he needed to "squeeze the brake pedal" on easing restrictions following a rise in coronavirus cases.
A further eight deaths were reported in the UK on Sunday, taking the total number of people who have died after testing positive for the virus to 46,201. However figures tend to be lower at the weekend due to reporting delays.
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