The Government risks "ghettoising" and isolating large numbers of disabled people if it pushes ahead with cuts to their level of support as part of the new Universal Credit, Baroness Tanni Grey-Thompson has warned.
The former wheelchair athlete said cuts to the level of benefits received by up to 450,000 disabled people under the Universal Credit would have a "serious impact" including running the risk of forcing some to drop out of work and sell their homes.
An inquiry headed by Lady Grey-Thompson, who shares the title of Great Britain's most successful female Paralympian with cyclist Sarah Storey, warns that three "key" groups of the disabled - including 100,000 disabled children - will be significantly worse off once the flagship reform is fully implemented.
"These are serious changes and I am passionate about disabled people being in work," she said.
"The danger is that if people lose that bit of extra support that keeps them in work, they drop out of work and they become ghettoised and isolated and it costs more."
Research for the study has shown that once the changes are fully in place, 100,000 disabled children stand to lose up to £28 a week, 230,000 severely disabled people who do not have another adult to help them could receive between £28 and £58 a week less and up to 116,000 disabled people who work could be at risk of losing around £40 a week.
The changes start to come into force from October next year and current benefit claimants who move on to Universal Credit will not see an immediate reduction in their payments. But they will have their level of benefit frozen, with no increases to take into account rising prices, campaigners said, and they may see their support cut immediately if their household circumstances change.
Anne McGuire, MP for Stirling and shadow minister for disabled people, who attended the House of Commons launch of the report, attacked the Government for attempting to "rubbish" its findings.
She said: "I find it astonishing that a child born on March 31 2013 who is disabled will receive - their family will receive - £1,300 more than a child born on April 1."
A spokeswoman for the Department for Work and Pensions (DWP) said savings from abolishing the adult disability premiums and changes in the child rate would be "recycled" into higher payments for more severely disabled people. She added that Universal Credit would provide greater incentives for people - including disabled people - to try out work and would reduce the financial and administrative barriers to work that exist in the current system.