Primary school children are self-isolating after testing positive for coronavirus, a school trust has confirmed.

The Jewish Academy Trust said a “small number of pupils” at Hertsmere Jewish Primary School, near Radlett, have tested positive for the virus – and three classes have been isolated as a result.

The trust is linking the cases to “social events” that occurred before the school opened for the new term.

Kirsten Jowett, chief executive officer at the trust, said: “There have been a small number of positive cases of children at the school. These are linked to social events before the school opened.

“On Public Health England advice we have isolated three classes,  due to contact with children that tested positive after returning to school. We have also sent parents correspondence on the situation from Public Health England."

She added that the trust is “disappointed” that some children are now having to learn from home.

She said: “We were all excited to be back at school. However, lessons will continue online. We hope parents will be vigilant in keeping to the national guidelines for social situations and that we can all get back to school as soon as possible.”

Yesterday, a senior councillor warned schools could close after a “significant” outbreak of COVID-19 in Hertsmere.

Hertfordshire County Council has said that large gatherings and house parties that happened in the Borehamwood area in late August are to blame for the spread of COVID-19, which has seen at least 60 people living in Hertsmere test positive over the last week.

Through contact tracing, the council says at least 200 teenagers have identified attending these parties.

But it seems that social events involving younger children have also caused the virus to spread.

Yavneh College is another school where it has been confirmed pupils are self-isolating, and it is understood there are other schools in the borough where similar action has been taken.

Cllr Tim Hutchings, executive member for public health in Hertfordshire, said: “We now need all residents in Hertsmere to pay really close attention to this serious issue of the spread of COVID-19, as well as working with community leaders, to remind them of the importance of following the government’s guidance to minimise the risks of the spread of COVID-19. If we do not get a grip on this local outbreak, then the risk is that schools may need to close.

“We have written again today to parents and carers of children at schools where fellow pupils are now playing their part by self-isolating, with a stern warning: stop these house parties and private events or face enforcement action of up to a £10,000 fine.”