More than four in five schools in England currently have children not in class because they cannot access a Covid-19 test, a survey suggests.

The majority (94%) of schools have pupils who have had to stay at home due to suspected or confirmed cases of Covid-19 this term – and more than three in four (78%) have had staff who had to self-isolate, according to a poll by the school leaders union’ NAHT.

Nearly nine in 10 (87%) have children not attending school because they are waiting for test results, while 82% of schools have pupils at home because they cannot access a test to rule out Covid-19.

The findings come after organisations representing heads and governors, including the NAHT, have implored Boris Johnson to “take charge” of tackling the testing delays to ensure schools remain open.

Paul Whiteman, general secretary of school leaders’ union NAHT, has warned that children’s education is being “needlessly disrupted” by a testing system which is in “chaos”.

One in seven (14%) of schools have had confirmed cases of Covid-19 since they began welcoming back students for the autumn term, the poll suggests.

The survey, of 736 school leaders over the past 24 hours, found that three in five (60%) have staff staying home because they are waiting for test results.

Nearly half (45%) of schools have staff not at work because they cannot access a test to rule out Covid-19.

Of the schools who have had to send pupils home due to suspected or confirmed cases of Covid-19 this term, nearly three in four (70%) have only sent home individual pupils.

But 7% have had to send home whole classes, 5% reported sending home whole year groups, and 4% sent home small groups of pupils.

Only 0.3% reported having to close their school, the survey suggests.

Mr Whiteman said: “Tests for Covid-19 need to be readily available for everyone so that pupils and staff who get negative results can get back into school quickly.

“But we are hearing the same thing repeatedly from our members across the country – chaos is being caused by the inability of staff and families to successfully get tested when they display symptoms.

It is unacceptable for this to happen when schools have put so much effort into getting their part of the plan right, and when pupils have had to endure so much uncertainty and disruption already

“This means schools are struggling with staffing, having to send groups of students home to isolate or close classes, and ultimately that children’s education is being needlessly disrupted.”

Mr Whiteman added: “It is in no way unpredictable or surprising that the demand for Covid-19 tests would spike when schools reopened more widely this term.

“And yet the system is in chaos.

“The Government has failed schools and children.

“It is unacceptable for this to happen when schools have put so much effort into getting their part of the plan right, and when pupils have had to endure so much uncertainty and disruption already.”

A Government spokesperson said: “The latest official statistics show that 99.9% of schools are open with the vast majority of pupils attending.

“Where staff or children have symptoms of Covid-19, testing capacity is the highest it has ever been, and we are working to provide further priority access for teachers.

“Schools only need to identify close contacts and ask them to self-isolate if and when a case is confirmed from a positive test result.

“Close contacts of confirmed cases must follow the full 14-day self-isolation period and should only seek a test if they have symptoms.”