More than four in five schools in England currently have pupils off sick because they cannot access a Covid-19 test, according to a survey.

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

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

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

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

One in seven (14 per cent) 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 per cent) have staff staying home because they are waiting for test results.

Nearly half (45 per cent) 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 owing to suspected or confirmed cases of Covid-19 this term, nearly three in four (70 per cent) have only sent home individual pupils.

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

Only 0.3 per cent 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.

“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.”