There is a "toxic culture of bullying" at a mental health charity, according to some of its former employees.
BBC Wales has heard a number of claims from former workers at Mind Cymru's Cardiff headquarters.
They claimed bullying was systemic and often involved staff being isolated and undermined.
The charity said it takes staff wellbeing "very seriously" and received only one bullying claim in the past two years, which was not upheld.
Mind Cymru employs 21 people and received almost £1.6m of Welsh Government funding over the past three years - part of its work includes offering advice on workplace bullying.
Andrew Jones worked for Mind between June 2015 and March 2016.
He said bullying was "very subtle" and felt as if his employer was "playing mind games".
"They will be picking you up on minor matters, unsettling you, isolating you from your colleagues," he added.
Mr Jones described a "vicious circle" of a drop in confidence, which had a detrimental effect on performance, leading to further criticism.
"It's almost like you're living hand-to-mouth in a war zone and you're constantly watching your back and, of course, the effect of that is really debilitating mentally and physically."
Mr Jones said "the gap between rhetoric and practice is huge" and "people's lives and livelihoods that are being ruined as a result of a toxic culture of bullying."
Louise Watkins left Mind Cymru in 2017 after two years at the charity.
She said she felt isolated and worthless after she told her employer she was feeling stressed.
"You hear the word bullying from school kids. As an adult you feel totally alone and you think is it my perception? But it isn't. You can't deny the way you feel. But I think as an adult you just feel stupid.
"Looking back now I wish I'd spoken up before I left. I wished I said something."
BBC Wales has heard further accusations from two other former workers who said they suffered similar treatment.
Since this story was first published, BBC Wales has been contacted by several more people who have worked at Mind offices around Wales.
They echo the concerns about the culture which they claim was damaging and unsupportive.
Mind's chief operating officer Paul Ward said: "We take the wellbeing of our staff very seriously and we are very saddened to hear that people who have worked for us feel they had a bad experience. We do not tolerate bullying and take any allegations extremely seriously.
"We always encourage anyone who has any concerns about bullying to report it, anonymously if they wish, and have clear management and HR processes in place to take action.
"There has been one allegation of bullying made by a member of Mind Cymru staff in the past two years. A full and robust investigation was conducted by HR and our senior team.
"The allegation was not upheld but we are committed to learning from staff experiences and continuously improving our practices. It would be inappropriate for us to comment further on this individual case.
"We are grateful that these issues have been brought to our attention and we are sorry if anyone has ever felt unable to share their concerns while employed by Mind.
"We would urge them to reach out to us directly now. We are keen to get to the bottom of what has happened and make sure that we are addressing any issues that might lead staff to feel unsupported."
Solicitor Bethan Darwin of Thompson Darwin Law said what amounts to bullying can vary in the eyes of the law.
Though it has a wide definition, she said it can be interpreted as "any way that makes that person feel that they are being belittled or undermined".
However, she added "there are two sides to every story as to what amounts to bullying and what amounts to good management. It's a very thin line between these two things".
Anyone who has had a similar experience please contact the BBC Wales news focus team on firstname.lastname@example.org