Although the report from the Disability Living Allowance Advisory Board also showed between 40 and 60 per cent of those entitled were not claiming, its report suggested several reforms which could cut down the number of claimants.
The benefits should be aimed at helping the most severely disabled, should be time-limited so that medical advances could be taken into account, it said, and should be backed by medical reports as well as lay advice.
Baroness Hollis, the social security minister, said the report provided an important insight into the need for welfare reform. However, it would be discussed with disabled people's organisations and other interested parties.
"I want to offer this important reassurance. Any changes to welfare provision will be reform-driven, not cuts-driven. The Government is committed to supporting disabled people in a way which promotes their independence," she said.
The report said there was a lack of evidence to support applications for Disability Living allowance (DLA) in two-thirds of cases. Just over two-thirds of awards were for life and the vast majority of the rest were for two years or more.
About half of DLA claimants and more than two-thirds of those on Attendance Allowances were not using aids or adaptations which could have helped to reduce their care needs.
There were now more than 8 million disabled people living in private homes, some 2.8 million more than suggested in a 1985 survey. This was partly because of the ageing population, partly because of care in the community and partly because of different survey methods.
The report was published among a batch of research on benefits as ministers and campaigners for disabled people agreed to formalise their consultations on benefits issues.
Last night, a spokesman for the DSS said that just because there was insufficient evidence in two-thirds of cases, that did not mean that requests for further information would lead to those people's benefits being cut.
Members of the Disability Benefits Consortium, which comprises a range of organisations including the Royal National Society for the Blind, Scope and the civil rights group Rights Now, met Harriet Harman, the Secretary of State for Social Security, and Baroness Hollis. Afterwards in a joint statement, the DSS and the consortium said: "This was a useful, lively and constructive meeting in which the consortium and the DSS agreed to take forward consultation on a formal basis.
"This includes a meeting to take place on 23 March to discuss the Benefits Integrity Project in more detail."
The project is a programme to assess disabled people to see if they still qualify for their benefits. After claims that it was causing injustice, Ms Harman last month announced a number of refinements.Reuse content