Thousands of badly performing pupils may have been excluded by state schools eager to boost their position in league tables, it is reported today.

More than 30,000 pupils have not had their GCSE results recorded in tables despite previously appearing on school registers over the last three years, an investigation by The Times found.

Schools inspectorate Ofsted said it was becoming “increasingly concerned” about the process known as off-rolling, adding that it was “never acceptable” to use exclusion to boost school performance.

The newspaper said there were 539,844 Year 10 pupils at state schools in 2016, but only 526,956 had their results included in league tables a year later - a drop of 12,888.

The number of pupils removed in the months before the exams for the past two years were 9,237 and 9,136, meaning 31,261 pupils have dropped out of the statistics since 2014.

Pupils moving abroad or relocating to non-state schools account for a proportion of these figures, the paper added.

But this figure also includes excluded students who have been sent to pupil-referral units (PRU) - with the investigation saying that 4,175 pupils were put in PRUs in the months leading up to exam season this year.

Matthew Coffey, Ofsted’s chief operating officer, said: “We are increasingly concerned about the scale of off-rolling apparent in some secondary schools.

“While we support the right of schools to exclude individuals who disrupt other pupils’ ability to learn, particularly those who exhibit violent or threatening behaviour, it is never acceptable to use exclusion to boost school performance.

Off-rolling ‘is breaking the law’

“We are undertaking further research to better understand this worrying trend.”

The analysis comes after FFT Education Datalab research, published in June, estimated that 22,000 children left mainstream secondary schools in England before the end of Year 11 in 2017, more than in each of the previous three years.

And while some of these pupils may have emigrated or moved to independent schools, as many as 7,700 Year 11 students were estimated to have left education entirely before taking their exams last year.

Concerns have previously been raised about off-rolling, with the children’s commissioner for England calling for schools to be fined if they are “gaming the system” by informally excluding low-achieving pupils ahead of the exam season.

Last December, commissioner Anne Longfield said it was “increasingly clear” that some schools were taking certain children off their rolls because “they think they won’t get good results”.

A Department for Education spokeswoman said: “Informal or unofficial exclusions are unlawful and we wrote to schools last year to remind them of the rules on exclusions. Any school ‘off-rolling’ on the basis of academic results is quite simply breaking the law.”