Prison governors have been accused of using the new national curriculum as an excuse to pare down courses to the bare minimum in the wake of savage budget cuts.
A core curriculum for prison education was introduced without fanfare a year ago to set minimum standards and focus prison governors' minds on the need to teach inmates basic skills.
But it has coincided with a prison population explosion and four years of tough funding cuts. Following a three-year 8.6 per cent cut to prison spending, at least 60 prisons were reported to have taken Pounds 300,000 from their education budgets.
Under the curriculum, prisons and young offenders' institutions must assess the prisoners' needs when they arrive, and provide minimum levels of education in literacy, numeracy, information technology and life skills.
It also lays down methods of recording their achievement. Standardised courses enable prisoners to continue programmes as they transfer between prisons, something that was not always possible in the past.
Since the introduction of competitive tendering four years ago most prison education has been provided by further education colleges.
Dan Taubman, assistant secretary of the lecturers' union NATFHE, said he feared that a basic curriculum provided a justification for cutting provision to the bone.
"That is what we think is happening," he said. "We have found some prisons have cut 80 per cent of their programme."
Penny Robson, the Prison Service's chief education officer, admitted: "One or two governors have used the curriculum as a reason to cut everything apart from basic skills.
"But if you take the whole picture, it has contributed to what feels to me to be a better education for the majority of prisoners."
The prison population has risen by more than half since 1992. But costs per prisoner have been cut by 3 per cent over the past two years, and further cuts of a similar scale are planned.
With governors left to decide where the axe should fall in their own prison, education has proved a soft target. Nationally, teaching hours per prisoner fell from 7.9 a week to 6.7 between 1995 and 1996 - and in some prisons, the number of hours taught have fallen by half.
It is thought that 50 per cent of prisoners have very poor literacy skills. Ms Robson believes that in the past the lack of formal assessment of new arrivals meant inmates effectively selected themselves for courses - and those who most needed help missed out.
She added: "I believe in a rich curriculum and the ability to learn liberal arts. But we have incredible numbers of prisoners with very poor literacy and numeracy, no information technology skills and very poor life and social skills.
"I don't want to have to justify a broad liberal arts curriculum when there are very scarce resources and we're turning out people who can't read. It has focused governors' minds on the idea that numeracy and literacy and core skills are very important. There is a need to prioritise."
Paul Cavadino, professional officer with the National Association for the Care and Resettlement of Offenders, said education was not the only casualty. However, the expansion of prison education in the early 1990s was now at risk.
Education was a key part of rehabilitation and protecting the public from repeat offending. "Without qualifications, there is very little chance of them getting employment," he added.