Former staff at Brewdog have alleged a „culture of fear” at the beer firm with a „toxic attitude” to junior employees.
In an open letter, signatories said a „significant number” of former staff had „suffered mental illness as a result of working at BrewDog”.
They claimed that the firm was built around a „cult of personality” of founders James Watt and Martin Dickie.
Mr Watt said Brewdog was „sorry” and that it would not contest the letter, but „listen, learn and act”.
The Scottish brewer is credited with helping make craft beer mainstream, after major supermarkets started stocking it in 2008. But it has also courted controversy for its marketing and commercial decisions.
In the open letter, which was posted anonymously on Twitter, from former staff made a number of allegations, including a culture where staff were afraid to speak out abut concerns.
It said Mr Watt and Mr Dickie had exploited publicity, „both good and bad” to further their own business goals and chased „growth, at all costs”.
It added: „You spent years claiming you wanted to be the best employer in the world, presumably to help you to recruit top talent, but ask former staff what they think of those claims, and you’ll most likely be laughed at.
„Being treated like a human being was sadly not always a given for those working at BrewDog.”
According to the letter, toxic attitudes towards junior staff had „trickled down” throughout the business „until they were simply an intrinsic part of the company”.
„Put bluntly, the single biggest shared experience of former staff is a residual feeling of fear. Fear to speak out about the atmosphere we were immersed in, and fear of repercussions even after we have left,” it added.
Along with many breweries and other parts of the hospitality industry, it has been hit by the coronavirus pandemic.
Mr Watt said: „At Brewdog we are focussed on building the best business we can, which is why the open letter we saw on Twitter was so upsetting, but so important.
„Our focus now is not on contradicting or contesting the details of that letter, but to listen, learn and act.”