Two primary schools have been forced to close after they became infested with false widow spiders.
Hundreds of pupils who attend The Osmani and Thomas Buxton Primary Schools in Tower Hamlets, east London, have been sent home.
In a statement Thomas Buxton School said the spiders can give a “nasty bite” and may cause an allergic reaction.
Pest controllers are at the scene and the school building and grounds will be fumigated “as a matter of urgency”, the school said.
The statement said: “It has been confirmed today that we have an infestation of false black widow spiders in the school grounds and building. The spiders can give a nasty bite which may cause an allergic reaction in vulnerable people.
“The safety and wellbeing of the children is our main concern so we have to take immediate action to deal with the problem.
“The entire school building and grounds will have to be fumigated as a matter of urgency. Therefore, we have no option but to close the school immediately. The closure is essential to safely fumigate the nests and remove the eggs.
“School will re-open on Monday November 23 at 8.55am. We are very sorry for the inconvenience and disruption to family life and also to the children’s learning.”
The spiders resemble the black widow and their numbers are reportedly on the rise in Britain.
A Tower Hamlets spokesman said: “The Osmani and Thomas Buxton Primary Schools are both temporarily closed due to a spider infestation.
“Pest control teams are currently on the premises of both schools, dealing with the infestation of false widow spiders. The spiders are not considered to be dangerous but do bite.
“Due to health concerns for staff and pupils the schools will be closed until next week.”
The council said it is not aware of any children at the schools being bitten.
The false widow (Steatoda nobilis) is about the size of a 50p coin and is the most dangerous of the 12 species of biting spider known in Britain.
Symptoms can include severe swelling, chest pains and tingling of fingers, with the severity depending on the amount of venom injected.