More than 1,500 people are receiving benefits due to mental and behavioural disorders, figures show.
The Employment and Support Allowance is provided to people who are struggling to work due to long term health conditions. It is available to those unable to work completely, and for people whose hours are limited by their condition.
Figures from the Department of Work and Pensions show 1,533 people in Powys were claiming ESA due to mental or behavioural conditions as of last summer – 43% of the 3,532 claimants in the area.
These conditions accounted for almost half of the 1.6 million people claiming the benefit across Great Britain and were the most common reason in every area and region.
In Powys, they were followed by 'musculoskeletal' diseases – which includes issues with joints, bones and muscles – with 502 people receiving ESA.
These figures show the primary diagnosis when people are first assessed for the ESA – there may be more people with mental health problems as a secondary condition which are not counted in the data.
She said: "We are concerned about the increasing rhetoric suggesting that benefits for disabled people and people experiencing long-term health conditions should be reduced. At the time of a cost-of-living crisis, this is unconscionable.
"People need to be offered tailored support from experts if they are to return to work, not threats of losing what little money they currently have to live on."
Fewer people are claiming the ESA as the Government moves towards using Universal Credit for those with health conditions.
As of December 2023, two million people were on Universal Credit health benefits, including 3,360 in Powys. This was a rise from 1.6 million (2,594 in Powys) a year earlier.
Data on medical conditions for those receiving the benefit is less complete than for the ESA, making it difficult to know the true number of people missing work due to issues with their mental health.
However, DWP figures show 72% of claimants starting on Universal Credit health benefits from 2022 to November 2023 were suffering from a mental health problem – even if this was not the main reason they were struggling to work.
The Joseph Rowntree Foundation – an anti-poverty charity – said these benefits are "inadequate" and can make people with mental health problems feel worse.
Senior policy advisor Iain Porter warned upcoming changes to the work capability assessment could cause hundreds of thousands of sick and disabled people to lose out.
The charity has called on the Government to implement an "essentials guarantee" to ensure people can afford basic items.
A DWP spokesperson said: "We are taking the long-term decisions to help everyone who can work to do so, improving lives and growing the economy.
"Our landmark welfare reforms will cut the number of people due to be put onto the highest tier of incapacity benefits by over 370,000 and instead give them personalised support, while our Chance to Work Guarantee will mean people can try work without fear of losing their benefits.
"In total our £2.5 billion Back to Work Plan will help over a million people to break down barriers to work, including those with disabilities and long-term health conditions."