School children are being denied access to water and toilet facilities, made to sit in cold classrooms and eat lunch standing outside, ministers have been told.
The "basic welfare" of pupils is being overlooked by "overzealous" teachers who are taking measures which they believe will mitigate the risk of coronavirus transmission, according to the parent campaign group Us For Them.
In a letter to the Education Secretary, schools minister and children's minister, the group reported: "Some of the cases we are seeing are extreme and many involve alarming issues of child welfare and safeguarding.
"Many children are faced with an array of measures which are disproportionate both individually and which together add up to a regime which is deeply concerning".
Molly Kingsley, co-founder of Us For Them, said said the group have received hundreds of reports from parents about schools going above and beyond what is required in official guidance.
"No one is policing this," she said. "Everyone is passing the buck so the schools have a free reign. Parents are having to police the Government's policies which puts them in an impossible situation."
Some parents reported that pupils were only given set time slots to use the toilets and are not allowed to go outside of these times, while others reported that children were told to always eat their lunch outdoors regardless of the weather.
Ofsted inspectors normally hold schools to account by inspecting them on issues such as children's welfare as management.
However, Ofsted says it is not responsible for the implementation of the Government's coronavirus guidance adding that it has no "scope to interpret or enforce this guidance".
"We need to understand who is responsible at Government level for overseeing that measures to control the virus are not implemented so egregiously that they cause harm," the letter to Gavin Williamson said.
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Ms Kingsley told the Education Secretary that Us for Them have sought legal advice on the issue and is prepared to bring a judicial review against the Government over its guidance for schools.
Earlier this week, the Children's Commissioner warned that overcautious teachers are sending entire year groups of pupils home unnecessarily, as she said that youngsters should "not be sacrificed on the altar of Covid". Just one pupil testing positive for coronavirus can send an entire school into "chaos" with a whole year group sent home for a fortnight, Anne Longfield said.
She wrote to MPs highlighting the huge discrepancies in the interpretation of guidance on how to handle cases of Covid-19 at school, and the detrimental effect this is having on children's education.