The union representing workers in the benefits system says reports that the vast majority of disabled claimants are fit for work should not be trusted.
The Public and Commercial Services union (PCS) which has thousands of members in the Department for Work and Pensions says the tests for claimants fail to address many serious health issues.
A House of Commons select committee report into incapacity benefit re-assessment - published on 13 July - said: "Our central conclusion is that the assessment process, as it is designed at the moment, does not accurately assess claimants' employability and needs in the workplace."
PCS general secretary Mark Serwotka said: "This exercise is just about saving money by bullying people who are sick or disabled onto lower levels of benefit.
"It is not about finding people work - because there are is no work available. The government is failing to create jobs, while cutting thousands of posts in the public sector.
"The government has given £100 million to a private health care company to do these flawed assessments - instead of using the health service which is already there and trusted by the public.
"The government have set up a system that demonises disabled people and will encourage bullying and hate crimes.
"Disabled people need more support - not less - to lead independent lives, including working lives."
PCS has produced a booklet: 'Welfare - an alternative vision' which has a chapter on disability benefit - see pcs.org.uk/welfare
- For information and interview requests please ontact Miles Barter, who is standing in this week for PCS national press officer Richard Simcox, on 020 7801 2744.
- The Public and Commercial Services union represents civil and public servants in central government. It has more than 300,000 members in over 200 departments and agencies, and in parts of government transferred to the private sector. PCS is the UK's sixth largest union and is affiliated to the TUC. The general secretary is Mark Serwotka and the president is Janice Godrich - on Twitter @janicegodrich
- Follow PCS on Twitter @pcs_union