Education Secretary Gavin Williamson has told Greenwich Council to keep schools open to all pupils or it will face legal action.
Schools in the south-east London borough were told to switch to remote learning for most pupils from Monday evening in a letter from council leader Danny Thorpe.
Council leaders in Waltham Forest and Islington also advised schools to move to online learning for the last few days of term as rising Covid rates in the capital saw Health Secretary Matt Hancock announce London will move to Tier 3 restrictions from Wednesday.
But on Monday evening, Mr Williamson issued a temporary continuity direction to the London Borough of Greenwich demanding it withdraw letters to head teachers and parents which advised schools to close.
The direction states it is enforceable by Mr Williamson making an application to the High Court or the county court for an injunction if the council does not comply.
The Education Secretary said in a statement: “It is simply not in children’s best interests for schools in Greenwich, Islington or elsewhere to close their doors.”
He added: “I have always been clear that using legal powers is a last resort but continuity of education is a national priority. That’s why I won’t hesitate to do what is right for young people and have issued a direction to Greenwich Council setting out that they must withdraw the letter issued to headteachers on Sunday.
“The Regional Schools Commissioner will continue to work closely with Greenwich Council and schools in the borough, as we have done with schools across the country, to support them with any operational challenges they face and ensure children can continue to receive face-to-face education.”
Mr Thorpe said the council was seeking legal advice and would respond to Mr Williamson on Tuesday morning.
“Schools across the borough have now organised online learning from tomorrow, whilst others are opening their premises to all pupils,” he said.
“We have alerted schools, and will speak to them tomorrow. But given we received this notification just before 5pm, it was impossible to ask schools to change any of the arrangements they have in place for Tuesday.”