A Labour MP says she has been told benefits assessments are like "psychological rape".
Laura Pidcock said the system for assessing people's rights to benefits amounted to "institutionalised bullying and harassment".
Work and Pensions minister Justin Tomlinson accepted it could be improved and said this was a "real priority".
But Ms Pidcock, the MP for North West Durham, said private enterprises and illness were "incompatible".
She had received a "vast number of submissions" from constituents and people using the system, she said.
"One person said that this process feels like psychological rape, expressly designed to make you feel like you are the absolute property of the state, that you are not human, and that your continued survival is a basic affront to society," she said.
'Focusing on improving'
Speaking in the same parliamentary debate, Labour's shadow work and pensions minister, Marsha De Cordova, called for private companies to be stripped of assessment work.
"Since 2010 more than £1bn has been paid to private contractors including Atos and Maximus and all of those providers have repeatedly failed by the DWP's (Department for Work and Pensions) own performance standards," she said.
"But despite their failures, the DWP recently announced they will be extending the contract for Maximus, and that contract will be extended until 2021."
Mr Tomlinson said the DWP was focusing on "improving the operational process".
Those involved were being given better training, he said.
He was committed to helping people "claim the benefits they are entitled to and to ensure people are treated fairly and with dignity", he said.