As many as 450,000 children could be removed from school special needs registers because they have been wrongly labelled as requiring extra help, the Government will announce today.
Campaigners fear the cuts could leave thousands of children "cut adrift". One in five schoolchildren in England is on the register.
The rules are designed to toughen up the diagnosis of behavioural and learning problems, amid concerns that schools are abusing the system to disguise poor teaching and climb league tables.
One in five children in England – about 1.7 million – is given extra help at school, many of them with problems such as autism, dyslexia and hearing problems.
The Department for Education will today announce that it is tackling "over-identification" by raising the threshold schools will have to meet to class pupils as special needs cases.