Thousands of sick or disabled people have died after being assessed to find out whether they were fit to work, the Commons was told.
MPs attacked Atos, the firm contracted to conduct work capability assessment (WCA) tests for the Government.
Former Labour minister Michael Meacher accused the firm of "ruthlessly" pressurising the sick and disabled into work.
Opening a Commons debate, he said 1,300 people had died after being placed in the "work-related activity group", for those currently too ill to be in a job but expected to take steps towards an eventual return to employment.
Some 2,200 died before the assessment process was completed and 7,100 died after being placed in the group for those entitled to unconditional support as they are too ill or disabled to work.
Mr Meacher said: "Atos is an IT firm and uses a so-called logic integrated medical assessment, often described as rigid and tick-box because computer-based systems make it very difficult for health professionals to exercise their professional judgment.
"Because such a mechanistic system has little or no regard to the complexity of the needs of severely disabled or sick persons, the British Medical Association and others have condemned the current WCA as not fit for purpose."
Mr Meacher continued: "The real fundamental issue is this: how can it be justified to pursue, with such insensitive rigour, 1.6 million claimants on incapacity benefit at a rate of 11,000 assessments every week when it has led - according to the Government's own figures - to 1,300 persons dying after being put into the work-related activity group, 2,200 people dying before their assessment was completed and 7,100 people dying after being put into the support group?
"Is it reasonable to pressurise seriously disabled persons into work so ruthlessly when there are already 2.5 million people unemployed and, on average, eight persons chasing every vacancy, unless they are also provided with the active and extensive support they obviously need in order to get and to hold down work, which is certainly not the case at present."