Fewer than 4 per cent of young people in prison studied GCSEs and A-levels last year, new figures show.
Only 439 of the 12,115 15- to 21-year-olds locked up during the 200708 academic year were enrolled on GCSE or A-level courses, despite many being long-term inmates who would have plenty of time to complete the qualifications.
Campaigners have urged teachers in young offenders' institutions to do more to help those in custody.
The 200708 statistics, revealed in a parliamentary question, show that 373 15- to 21-year-olds began GCSEs, and 66 started A-levels.
Penelope Gibbs, director of the Prison Reform Trust's programme to reduce child and youth imprisonment, said GCSE and A-level enrolment rates were not high enough.
"The problem is, young adults are moved around from prison to prison and there's no continuity making it hard to study a course as long as A-levels and GCSEs," she said. "Not having these qualifications makes it hard for them to find a job, which means they face the same problems as anyone else without exams.
"But young prisoners are doubly disadvantaged because they have been in jail, and all the evidence shows if you don't have a job, you are much more likely to reoffend.
"I heard from one head of education in a secure unit who, when trying to find a school place for a bright boy, was told there was no space. When she enquired without mentioning he had been in custody, the school said they could accept him."
At the end of the 2008 academic year, more than 1,000 15- to 17-year-olds and more than 5,000 18- to 21-year-olds were serving sentences of more than a year.
Changes to the law mean that, from next year, young inmates will have the same rights to education as other children. The number of hours of teaching they will be entitled to each week will increase significantly from 15 to 25.
The legislation, brought in to make sure that the UK complies with the United Nations Committee on the Rights of the Child, will also pass control over the education of young offenders from the Learning and Skills Council to local authorities, which will have responsibility to "promote" learning for young offenders from their area.
An annual total of #163;7,628 is now spent on education for every young offender - considerably more than is given to schools per pupil.
Analysis, pages 26-27.