An internal email sent by senior managers warns that ill-handling of benefit changes could have 'profound results' for vulnerable claimants

Senior jobcentre executives have warned staff of the risk of benefit claimants attempting suicide as controversial changes to sickness benefits are being pushed through.

The warning, contained in an internal email sent to staff by three senior managers of the government-run jobcentres, warns staff that ill-handling of benefit changes for vulnerable claimants could have "profound results" and highlights the case of one suicide attempt this year.

It emphasises the need for the "utmost care and sensitivity" when dealing with customers, as a result of "difficult changes which some of our more vulnerable customers may take some time to accept and adjust to".

The email, adds: "Very sadly, only last week a customer of DWP [Department for Work and Pensions] attempted suicide" – which it adds is "said to be the result of receiving a letter" informing him that his sickness benefit would be cut off.

The memo will crystallise concerns among charities, campaigners and medical professionals over the impact of welfare reforms on the mental health of some of Britain's most vulnerable people.

Disability campaigners privately warned ministers last year that flaws in the work capability assessment, would lead to some mentally ill people taking their own lives. But they said they were accused by ministers of scaremongering.

Neil Coyle of the charity Disability Rights UK, said: "The government is cutting direct support for thousands of disabled people and using a process to do so which is unfit for purpose. The assessment process for out of work benefits needs urgent improvement to ensure genuine needs are identified properly and to avoid further tragic consequences.

"We and our members warned the government – and DWP especially – of the impact of cuts in support but the problem has been swept under the carpet in the rush to deliver cuts in welfare expenditure. Numbers on a balance sheet have been considered more important than the lived reality of disabled people sadly."

The memo was sent in late April, days before the controversial change of time-limiting contributions-based employment and support allowance was introduced, which will see thousands of sickness benefit claimants with a working partner or some savings lose up to £91 a week in support.

The email sent to jobcentre staff emphasises the importance of being "empathetic" with vulnerable clients, "taking the time to properly understand their circumstances … and talking through their options or signposting them to other sources of support/advice". It adds: "The consequences of getting this wrong can have profound results."

The Rutherglen and Hamilton West Labour MP Tom Greatrex said: "The DWP should take seriously the potential impact its decisions can have on people's lives.

"The 'one size fits all' nature of the work capability assessment is at the root of the problem. A crude computer test of fitness to work leaves little room for a consideration of the affect on mental health.

"It's not just those with pre-existing mental health problems who are at risk. People suffering from conditions such as Parkinson's and cancer find themselves in distressing situations, with added anxiety caused by these tests. At a time when they need help, too often they feel they are being hounded."

A DWP spokesperson said: "It remains rare to find incidents of self-harm where the benefits system is said to have been a factor, but we are not complacent when it comes to ensuring that our staff can provide the right support and help to those affected.

"We ensure our staff are highly trained and ready to help people, however vulnerable they may be and whatever pressures they face.

"We have worked hard – and continue to do so – to improve the way the work capability assessment works for those with mental health issues, but it is right to reform the welfare system. The old incapacity benefits system let down too many people by simply writing them off to a life on benefits, which did nothing for their wellbeing."

But the Public and Commercial Services (PCS) union, which represents Jobcentre Plus staff, says that they feel ill-equipped to deal with the volume of work, vulnerable claimants and cutbacks.

One jobcentre telephone adviser told the Guardian that the change had been handled "abysmally" and that they feel ill-equipped and "helpless" when talking to distraught customers on the phone, who are phoning up to ask about other options.

"A lot of them are very distressed. They are asking us what to do … how are they supposed to live. And there's nowhere else we can signpost them to, there's literally nowhere for them to go."

Several coroners' reports into suicides have mentioned benefits decisions as a contributory factor, but ministers have always been careful to avoid acknowledging a link.

The Guardian has spoken to dozens of benefits workers and recipients as part of an investigation into the problems faced by Britons living on the breadline and identified three separate cases of attempted suicide among people where changes to their benefits appeared to have been a factor. Several others claimed to have felt suicidal.

Speaking in the Commons recently, the employment minister, Chris Grayling, said: "We will always look very, very carefully indeed where something like that happens. So far my experience is that the story is much more complicated. But that does not mean we are not doing the right thing.

"I passionately believe that we should be helping [people], particularly those with mental health problems. I have met people who have been out of work for years and years and years with chronic depression who we are now beginning to help back into work. We have got to be very careful but we do look very carefully when those situations arise."