Iain Duncan Smith faced a huge backlash yesterday over his latest "crackpot" scheme to hack away even more of disabled people's vital benefits.

More than half a million people considered unfit to work because of serious illnesses are at risk from the Tory Work and Pensions Secretary's plan.

The work-related activity group - sufferers of recent illnesses who are deemed capable of work in the future - receive benefits as long as they participate in training exercises and practice interviews.

Mr Duncan Smith thinks the group, made up of 546,770 people, should be disbanded because half of the claimants will not be able to work for at least three years, according to the Observer.

He is concerned that administration and appeals are costing hundreds of millions of pounds and thinks claimants should be moved onto jobseeker's allowance.

Campaign group Disabled People Against Cuts said the plans were "just another crackpot idea that will cause disabled people to live in fear."

Co-ordinator Linda Burnip said: "It will just end up costing the government more. There will be more people needing long-term care for mental and physical ailments because of the added pressure and removal of support."

The plan is the latest in a host of Con-Dem measures affecting people with disabilities.

They include the bedroom tax, changes to incapacity benefit and a thwarted attempt at abolishing the independent living fund for people with serious disabilities.

Labour MP Anne Begg, the chairwoman of the work and pension select committee, said: "I have two constituents who are psychiatric nurses who have just been telling me about the damage done to people who are ill and incapable and forced to attend jobcentres.

"We have all these people who they are wasting money on trying to get into work, who are realistically never going to get into work and whose condition will be made worse," she told the Observer.

Mr Duncan Smith is believed to be pushing for the measure to be included in the forthcoming national disability employment strategy.