Healthcare company 'takes complaints seriously' but says it only runs assessments and that decisions are made by the DWP

The executive in charge of running medical assessments for benefits claims at Atos Healthcare has offered an apology to those long-term sick it has incorrectly assessed as being "fit for work".

In her first public interview, Lisa Coleman, the manager who oversees the firm's contract with the Department for Work and Pensions (DWP), was asked by BBC Radio 4's You and Yours programme if she would like to apologise. She replied: "If we get something wrong then I'm very happy to say sorry."

Although work capability tests were introduced by the Labour government in 2008, the coalition has rapidly expanded their use. However, Atos – which last year processed almost 20,000 incapacity benefit claimants a week – has faced criticism after it emerged that a third (37%) of decisions appealed were successfully overturned.

There have also been repeated claims that people with terminal cancer had been denied benefits as a result of Atos assessments and that the company sets out to strip people of benefits by making the tests arduous and degrading.

Radio 4 questioned Coleman about a number of cases in which people had claimed that their complaints had been ignored, that assessments had not been carried out properly or that no account was made of the needs of patients – some of whom could not stand or needed nursing support – to take the tests.

Coleman said Atos "did not have targets for taking people off benefit. We take complaints seriously. If there's way to improve then we're happy to take that feedback and improve [the service]. If we get it wrong then happy to say we got it wrong."

But, she added, Atos did not make decisions on what benefits people received, and its responsibility was only with properly conducting the assessments. "The Department for Work and Pensions make decisions. We don't make decisions."

The company claims that "recent figures released by the DWP suggest that of the 15% of (fit for work) decisions successfully appealed[ against], Atos reports are a reason for successful appeals in only 0.3% of cases".

Although the coalition has conceded that the assessments could be improved, there is little doubt that ministers intend to increase their role in the welfare system. Ministers claimed last month that 878,000 people who were on incapacity benefit dropped their claim to the payments rather than undergo a tough medical test. The Conservative party chairman, Grant Shapps, said the figures "demonstrate how the welfare system was broken under Labour and why our reforms are so important".

But it later emerged that this figure was calculated by adding up the 20,000 claimants every month who leave the benefit system without undergoing a work capability assessment over four years – which DWP's own research says is largely owing to the fact many people will see an improvement in their condition, or will return to work regardless of whether their condition improves.

At the beginning of April, Atos began a £400m, five-year contract carrying out tests for the new personal independence payment (Pip), which replaces the disability living allowance and determines whether people are entitled to extra money to help cope with disability, such as cars, equipment or nursing.

A DWP spokesman said: "We are committed to helping thousands of people move from benefits and back into work if they are capable, while giving unconditional support to those who need it.

"Since 2010 we have considerably improved the work capability assessment process. As a result, the percentage of people getting long-term unconditional support has more than doubled in two years."