The prime minister has insisted that “schools are safe”, arguing that the problem lies with the household mixing that “naturally takes place” there.

Speaking at the Downing Street briefing this afternoon, Boris Johnson said it was “right” for parents to send their children to primary school from next week outside of “very, very high infection rate areas”.

His comments come after the education secretary announced that primary schools in areas particularly badly affected by the virus will remain closed for at least two weeks from Monday.

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The prime minister was asked: “If you’re a parent of a primary child in a Tier 4 area, but your school is reopening next week, are you still legally obliged to send them if you’re worried about infection rates?”

He replied: “The message is: schools are safe. The problem is not the schools. Teachers, school authorities, parents, they made a fantastic effort to make schools safe places.

“The issue is what happens...the spread from the mixing of households that naturally takes place in schools, that’s what we’re trying to combat in the very high infection rate areas.

“So my message would be unless your area specifically is identified as being amongst those very, very high infection rate areas, send your children, send your family to school in the normal way. Absolutely, absolutely right to do.”

But teachers leaders have a different take. Mary Bousted, NEU joint general secretary, said she was “astonished” that most primary staff and pupils were being sent back into schools “which aren’t Covid secure”.