Participation in adult learning is at its lowest level since Labour took power, with the poor and manual workers among the hardest hit.
The party's traditional heartland has been worst affected by the shift to work-based training, according to the annual survey by Niace, the adult learning body.
"Narrowing Participation" notes that at the peak in 2005, 40 per cent of skilled manual workers would have been involved in learning in the previous three years. Now only a third are, which equals the 1996 figure. Participation among all adults, at 18 per cent, is at the lowest level since 1997 says the report, published to coincide with adult learners' week, which starts tomorrow.
Alan Tuckett, director of Niace, said the findings suggested a small number of the least skilled were making gains at the expense of many more of the poorest adults with the fewest educational opportunities.
"Ministers couldn't see the relationship between what people were studying and industrial change, and so they thought there wasn't one," he said. "Their targets are barriers to providers being responsive locally to the wider needs of different people. It benefits a fragment of the population. There aren't any participation targets."
The findings also challenge the claims of ministers that their policy would target supposed middle-class courses such as holiday Spanish.
David Blunkett, the former education secretary who published "The Learning Age" green paper and set the stage for a substantial increase in adult education, said the findings showed the need for more equality of access to courses.
"The widening gap in participation in adult learning between professionals and the unskilled merely reinforces the Campaigning Alliance for Lifelong Learning aims set out at the recent lobby of Parliament, which I fully support," he said.
The unskilled and unemployed were most likely to learn through a publicly funded institution, suggesting they are at risk of being left behind through emphasis on the work-based Train to Gain scheme.
While 52 per cent of unskilled workers who had been learning said they had attended an institution such as a college, the figure fell to 39 per cent of professionals, who were more likely to get training at work.
But some unskilled workers were also the most resistant to learning, with more than a quarter saying no changes to the system would encourage them to re-enter education.
A Department for Innovation, Universities and Skills spokeswoman said: "Often people with lower skills from lower socio-economic groups need longer, more valuable courses like Train to Gain or basic skills.
"There may well be fewer people participating overall, but what they are doing will have much more value, lead to higher earnings and better employment prospects."
The investment in basic skills for 3 million people since 2001 had benefited lower socio-economic groups most of all, she said.