The nursing regulator is facing questions over why it has been unable to clarify how many disabled people have lodged complaints about nurses who have carried out disability benefit assessments for government contractors.

Disability News Service (DNS) has been trying since December to secure accurate figures showing how many complaints have been lodged with the Nursing and Midwifery Council (NMC) about the conduct of nurses carrying out assessments for personal independence payment (PIP) and employment and support allowance.

Many benefit claimants have raised concerns about the apparent refusal of NMC and the Health and Care Professions Council – which regulates paramedics and physiotherapists – to take seriously their complaints about healthcare professionals who carry out assessments.

NMC originally responded to a DNS request with figures that showed the regulator had received more than 1,600 complaints in the last five years about nurses working for Atos, Capita and Maximus.

The figures were published as part of an ongoing DNS investigation that has showed how healthcare professionals – mostly nurses – working for Capita and Atos have lied, ignored written evidence and dishonestly reported the results of physical examinations in PIP assessment reports compiled for the Department for Work and Pensions (DWP).

But early last month, NMC withdrew the figure of 1,600 complaints, blaming its failure to use the correct terms in searching its database. It also said the data it had provided had not been “manually checked or filtered”.

It then provided – on 6 February – new figures which suggested that there had been only 29 complaints in the whole of 2016 across the three assessment companies, including just three complaints lodged against Capita nurses, one of which had to be abandoned because of a failure to secure consent.

DNS subsequently questioned the NMC statistics because at least two PIP claimants had come forward to describe how they had lodged complaints about Capita nurses last year.

DNS told NMC on 10 February that it was highly unlikely that the only two disabled people in the country to have lodged such complaints had also been involved in the DNS investigation.

Since then, NMC has repeatedly had to apologise to DNS for its failure to confirm whether the new figures it provided related to those dealt with by its “screen legal team”, which logs initial complaints about nurses and midwives.

DNS contacted NMC again this week and the regulator has still not been able to provide an explanation for its failure to provide accurate figures for complaints against nurses working for Capita, Atos and Maximus.