MPs have launched an inquiry into why so many disability benefit decisions are being overturned on appeal, and look set to examine claims of widespread dishonesty among the healthcare professionals who carry out assessments on behalf of the government.

The investigation by the Commons work and pensions select committee follows a previous inquiry into the personal independence payment (PIP) assessment process, which had to be abandoned when the prime minister called a snap general election earlier this year.

The committee will ask how the assessment processes for both PIP and employment and support allowance (ESA) are being handled by the private sector contractors Atos, Capita and Maximus.

It will also look at how the application and appeals processes are working.

The committee said – crucially – that the evidence it received in the last parliament revealed “worrying disparities” between how claimants described their face-to-face assessments and the final reports passed to the Department for Work and Pensions (DWP).

And it said that concerns were also raised about the “dignity and conduct” of the assessment process and the ability of the assessors to “understand and properly assess” conditions.

The latest figures, the committee said, show 65 per cent of appeals that reach the tribunal stage are successful, for both PIP and ESA, while the number of appeals had risen by nearly 30 per cent in the last year.

Earlier this year, Disability News Service (DNS) provided the committee with substantial evidence of widespread dishonesty in the reports compiled by PIP assessors from the discredited outsourcing companies Capita and Atos.

That evidence helped trigger an urgent evidence session of the committee, but none of the four welfare rights experts who gave evidence were asked by the committee’s MPs about claims of dishonesty.

DNS had told the MPs how its investigation revealed that assessors working for Capita and Atos – most of them nurses – had repeatedly lied, ignored written evidence and dishonestly reported the results of physical examinations.

The committee’s latest call for evidence appears to show that it has listened to criticism of its previous approach and that it will now examine these claims of dishonesty.

DNS has so far received more than 250 such claims from PIP claimants, and is likely to submit updated evidence to the committee.

One of those who has submitted evidence to DNS as part of its investigation is Mary*, who has experienced dishonest assessors both with her own PIP assessment and her husband’s.

She said it was a “huge relief” to hear of the inquiry.

She said: “We sincerely hope the extent of this widespread systemic malpractice will be fully exposed for what it is, putting an end to the dishonest healthcare professional reports and the abject failure of both the healthcare professionals and the DWP case managers to follow the DWP PIP assessment guidance and correctly apply the actual legal threshold for PIP.

“There will then need to be an extensive clean up of the fraudulent reports and false statements that are currently on the system about individual claimants.”

Frank Field, the under-fire chair of the work and pensions committee, said the rate at which ESA and PIP decisions were overturned was “truly amazing”.

He said this suggested something was “fundamentally wrong” with how face-to-face assessments and mandatory reconsiderations – DWP’s internal reviews, the first stage of the appeal process – were being carried out.

He said: “Quite apart from the human cost this represents – the distress and difficulty for applicants trying to get help with daily living or getting into work – it looks to be wasteful, inefficient, and a huge cost to taxpayers.”

Field called for evidence on the assessment system from both claimants and assessors.

Any evidence should be submitted to the committee by 10 November.

Meanwhile, Maximus has announced that its contract to deliver the work capability assessment – which assesses eligibility for ESA – had been extended by the government by a further two years, until March 2020.

*Not her real name