The architect of a new benefits system has said radical changes must be made to avert serious problems for vulnerable people, according to reports.
Paul Gregg, Professor of Economics at the University of Bristol, told The Times serious adjustments are necessary before 2.5 million incapacity benefit claimants are moved onto the new employment and support allowance (ESA) in October.
In its current form, the system leaves large numbers of failed claimants to languish on jobseeker's allowance with no prospect of work, he said.
Reflecting on perceived errors in the process, he told the paper: "To go ahead with these problems is not just ridiculous. It is, in fact, scary."
All new claimants who would have sought incapacity benefit have had to apply for ESA since October 2008 - but according to the paper, thousands of vulnerable people with terminal cancer, Parkinson's disease, multiple sclerosis and clinical depression had their applications declined and were told to look for work.
"Introducing the ESA system for new claimants in 2008 was effectively a pilot, and all the signals from the pilot are that a lot of adjustments need to be made," Prof Gregg said.
"There are serious problems with putting people who failed the test but still have serious health or other issues straight onto jobseeker's allowance, where there is no special help," he added. "To start moving people who may have been on incapacity benefit for years straight onto jobseeker's is ridiculous. Before wading into the stock, the system has to be right."
The drive behind ESA is to focus on what people can do rather than what they cannot do, as a means of getting them back to work.
The process was previously condemned for failing the seriously ill and disabled. A joint report last year by Macmillan Cancer Support and Citizens Advice found people in hospital were wrongly refused ESA and noted cancer sufferers were being told they were fit for work when they were battling long-term effects of the disease.
But Chris Grayling, Minister for Employment, told the paper there would be no change to the timetabled plans. "We have to start helping those two and a half million people who've simply been left behind on the incapacity benefit," he said.