An all-through school has become the tenth to confirm it will close for false widow spider treatment.

School 21, in Stratford, will be shut on Monday and Tuesday, with the possibility that it may need to be for longer.

A letter to parents from headteacher Oli de Botton said that the school has highlighted a ‘medium risk’ inside the building.

He wrote: “Although pest control’s original assessment was that the risk was low inside the school, they did identify spiders on the outside of the school, largely in the crevices of the shutters that cover the outside of the building.

“On this advice we were originally intending to keep the school open next week (with risk mitigations in place) and treat the outside over half term.

“However, a second review this morning highlighted a medium risk inside linked to a sighting.

“It is possible that in the review process a spider from outside was disturbed and came in.

“The advice now is that we apply treatment both inside and outside - and do so over the next few days.”

He added: “At this stage it is worth bearing in mind that the period between the treatments may be difficult to manage - the spiders will have been disturbed and as such may be more active.

“If we feel they pose a significant risk, we may need to close for additional days next week. Again this will be with great regret.”

Mr de Botton has said that he will be searching for venues to hold classes for pupils in Year 6, 11 and 13, while planned school trips, work placements and a primary school performance will all be going ahead. Pupils in the secondary section of the school will also be sent work to complete at home.

The announcement comes as four of the previously closed schools are set to reopen next week. Three others will remain shut until the half term break.