The boss of BrewDog has been accused of trying to intimidate former staff who are due to appear in a critical documentary that will shine a light on the beer brand’s workplace culture. The self-styled “punk” brewery, which is targeting an eventual £2bn stock market float, apologised last year after current and former employees signed an open letter alleging a “culture of fear” in which workers were bullied and “treated like objects”. Some of the allegations will be revisited in a BBC documentary, Disclosure: The Truth About BrewDog, due to air on Monday evening. But in fresh posts on BrewDog’s “Equity for Punks” forum, the company’s chief executive, James Watt, appeared to attempt to warn sources who gave evidence to the BBC that their identities could be exposed. In the forum, which is seen by investors and some staff, he said: “All of this is very, very likely to end up in court.” He said the BBC “will likely have told sources that their identity will remain anonymous”. But he said anonymity “can never be guaranteed” and a court could order the BBC to name former staff who contributed to the programme. “If anyone is in any way concerned by this, it is not too late to withdraw your consent,” he said. A spokesperson for the Unite trade union criticised Watt’s comments. “Any attempt to intimidate current and former workers taking a stand on systemic mistreatment will not be tolerated,” said Bryan Simpson, an industrial organiser for Unite Hospitality. “We will represent all Unite members fully against efforts by a multimillionaire to silence them.” Watt said: “We … know false information has been given to the BBC, which if broadcast would be highly defamatory. BrewDog fully supports transparency and investigative journalism. However, it must also protect itself from defamatory allegations and will not hesitate to do so.” Last year 61 former workers signed an open letter under the banner “Punks with Purpose”. They alleged that the Scottish brewer’s dizzyingly rapid growth had involved cutting corners on health and safety, espousing values it did not live by, and creating a “toxic” culture that led to staff suffering from mental illness. The company, whose meteoric rise has attracted admiration as well as criticism for its sometimes controversial PR stunts, has since apologised and performed a review of its workplace culture. Watt has repeatedly promised to learn from the experience, while also casting doubt on the integrity of some of the complainants. Disclosure: The Truth About BrewDog is on BBC One Scotland on Monday 24 January at 7pm and will also be on iPlayer.