A London council has asked all schools in its borough to close and move to online learning following an “exponential growth” of Covid cases, but some are set to defy the request.

On Sunday evening Greenwich council leader Dan Thorpe sent an open letter requesting all schools close as the pandemic is “now escalating extremely quickly”.

But two schools – Ark Greenwich Free School and Harris Academy Greenwich – have already said they will not close early in response to the council’s request.

It comes after Schools Week revealed the Department for Education was issuing legal threats to schools that were attempting to move to online education in the final week of term.

The DfE has insisted schools must remain open until Thursday, and some settings have been sent ‘minded to direct’ letters from schools minister Nick Gibb. Under coronavirus legal powers, the government can apply for a high court injunction to ensure schools remain open.

But Thorpe said the situation in his area demanded immediate action.

“We now have the highest rates of infection in Greenwich than at any time since March, and for these reasons I have therefore asked all schools in Greenwich to close their premises from Monday evening and move to online learning for the duration of the term.”

He added that there should be an exception of key worker children and those with specific needs – as there was during the partial school closures earlier in the year.

However some schools have already voiced their intention to defy Thorpe’s request and remain open.

Rhys Spiers, head teacher at Ark Greenwich Free School, sent a letter to parents informing them the schools would remain open until Thursday.

“I will of course continue to monitor the situation closely, however until I am instructed to close by the government Department for Education (DfE) and/or Public Health England (PHE) our school will remain open to all scholars as normal.”

Harris Academy Greenwich also tweeted that it intends to remain open to all year groups except years 8 and 9 until Thursday “Covid cases permitting”. Years 8 and 9 are self-isolating following a positive result of Covid-19.

Islington Council is also advising schools to move to online learning from the end of day tomorrow (Tuesday).

Council leader Richard Watts added: “We must all take action now to stop this deadly disease spreading serious illness and death to the people we love.

“This is a very difficult decision – however the public health situation in Islington and London is so serious that we have to do everything we can to stop this deadly virus spreading in our community and across London.”

Elsewhere Essex County Council revealed that eight out of nine secondary schools in Basildon have moved to full remote education, while 17 out of 48 primary schools have also followed suit.

Last month the DfE revealed a new contingency framework which saw ministers seize control of the restrictive measures schools can apply to fight the spread of Covid-19.

It warns that schools “should not move to implement restrictive measures of the kind set out in the contingency framework without the explicit agreement of DfE”.

Geoff Barton, general secretary of the Association of School and College Leaders, said it was a “chaotic situation”.

“It is deeply unfair on school leaders, teachers, families and pupils that they are caught between the heavy-handed approach of central government and increasing alarm at local infection rates.”

Barton called on the government to “remove the threat of legal action and allow schools to make the decisions they need to make on behalf of their staff and children”.

Last night London mayor Sadiq Khan voiced his support for the closure of schools in the capital.

A spokesperson for the mayor told the Daily Telegraph: “The mayor is backing the early closure of schools and would like the government to consider shutting schools from Tuesday.

“He wants tomorrow (Monday) to be the last day at school.”

A DfE spokesperson added: “It is a national priority to keep education settings open full time and it is vital that children remain in school until the end of the term.”