Some bright pupils are being asked to re-take GCSEs to boost the overall results of their schools, it has been claimed.
Independent tutoring expert Dr Mike Ryde claimed some of his young pupils were being asked by their own school to re-sit exams they had taken early at his college, because they had been awarded top marks.
He said: "I have had it a few times, pupils have come to me and said 'my school wants me to take it again'.
"This is because if they know a child is going to get a good mark then they want it to count towards their school's performance."
The performance of schools is judged in part on their GCSE results, which feed into annual national attainment tables.
Dr Ryde is the head of Ryde Teaching Services in Watford, which teaches children below the usual GCSE age. Children can take GCSEs with his college as it is also an assessment centre. But he claimed some schools were then asking pupils to re-take the exam at their own school.
He said: "I had one school call me and ask if they could say a pupil had taken the exam with them because he had got a good grade."
Dr Ryde said more schools should put pupils in for GCSEs early, to reduce the pressure on them to take all of their exams at the age of 16. But he claimed most fail to do so because results of exams taken by younger pupils will not show up in their attainment tables.
A spokeswoman for the Department for Children, Schools and Families said: "Whether a pupil sits a GCSE exam early is a decision for themselves, their parents and the school to take.
"A school may suggest to a pupil that they re-take an exam if it is in the pupil's best interests because they are likely to get a better grade. We would be very surprised to hear of schools asking pupils to re-take exams for any other reason."