Thousands of pupils and staff are now absent from London’s schools because of Covid-19, an investigation reveals today.

Almost 20 per cent of students in some parts of the capital are not attending lessons and Newham had more than 3,000 pupils self-isolating last week, according to data obtained from councils.

The figures have prompted warnings that schools will struggle to stay open unless teachers are regularly tested.

They show that last week, 3,126 children in Newham were self-isolating along with almost 200 school staff. The borough has the highest number of school-aged young people in London.

In neighbouring Barking and Dagenham, 1,401 pupils were at home and in Tower Hamlets, where 46 schools have had at least one confirmed case of coronavirus since they reopened, attendance was at just 81 per cent at secondary level — almost 15 per cent lower than it was on average last year.

The council said 1,582 pupils were self-isolating.

The eastern boroughs have some of the highest rates of Covid-19 in London but the virus has hit school attendance throughout the city.

Councillor Zulfiqar Ali, cabinet member for education in Newham, said: “It is deeply regrettable that any child should miss school because of the Covid-19 crisis, but keeping symptomatic children and staff away is the only way to keep the schools open and safe for the vast majority.

“The government’s failure to provide adequate testing is unnecessarily keeping pupils and staff out of school. If testing were easily accessible and speedy – pupils and teachers with a negative tests could return to class before the 14-day quarantine period.

“I salute the brilliant work done by our schools in keeping our classrooms open to the vast majority of our children.”

Barking MP Dame Margaret Hodge has written to health secretary Matt Hancock demanding that teachers have Covid tests every week to help keep students in lessons.

“While the local authority is taking every possible step to mitigate risks, they have warned that without regular testing for teachers it will be very difficult to keep all schools open,” she said.

“As one of the most deprived areas in London, young people in my constituency simply cannot afford to miss out on their education.”

A Department for Education spokesman said the government is continuing to improve the testing system to ensure teaching staff can get priority access when they have symptoms and it has put more than £100million into supporting children to learn at home.

He added: “Only a small minority of pupils are currently self-isolating, in response to public health guidelines to keep us all safe. Teachers are being prioritised to access tests where they have symptoms.

“We have also recently expanded our offer of remote education assistance for schools and pupils, providing an extra 100,000 laptops for disadvantaged children on top of the 150,000 previously announced, bringing the total allocation as stands to 250,000 for this term.”