Ofsted's annual report has provided a damning assessment of secondary schools undertaking 'off-rolling' and has identified a 'worrying gap' in the provisions for schools attended by pupils with special educational needs or disabilities.
The education watchdog warned that thousands of pupils could be "disappearing" from the school system as a result of illegal off-rolling.
The report found that 19,000 children dropped off school rolls between January 2016 and January 2017, during the time that students are undertaking their GCSE exams.
Around half (9,700) of those dropping off rolls between Years 10 and 11 are not reappearing on the roll of another state-funded school.
'Off-rolling', a practice where schools move difficult-to-teach pupils off their rolls to boost performance data, is illegal and leaves the child without access to educational support.
Commenting on the report by Ofsted, Liberal Democrat Education spokesperson Layla Moran said:
"It is shameful that thousands of children are being let down in this way. Every child has the right to an education and should be supported to achieve to the best of their ability in our schools.
"This Government is fostering a culture of senseless competition between schools, where results from a single set of narrowly focused, high-stakes exams, are made to feel like the be all and end all when it comes to judging a school's success.
"All this does is force schools to give up on pupils who are struggling - a decision which will have devastating consequences for their education, job prospects and self esteem for years to come."