Prince Harry was branded the "number one risk" to his charity Sentebale by the chair of the organisation in an explosive interview on Sunday morning.
Dr Sophie Chandauka has previously accused the Duke of Sussex of "harassment and bullying at scale".
Dr Chandauka alleged that Sentebale, which was set up by Prince Harry in 2006 to help young people with HIV in Lesotho and Botswana, lost sponsors and donors when the Sussexes left the UK.
A source close to Prince Harry and the former trustees has denied her claims as "completely baseless".
The chair of Prince Harry's charity Sentebale has called him the "number one risk" to the organisation in an explosive interview on Sunday morning
PAThe charity was established in memory of Harry's mother, Princess Diana.
Dr Chandauka claimed that when she raised concerns about lost sponsors, she was told it was "an uncomfortable conversation to have with Prince Harry in the room".
When asked if donors were leaving because of the prince's reputation, she replied: "Yes."
She also alleged that Prince Harry tried to "eject" her from the organisation.
Dr Sophie Chandauka has refused to step down as the chair of SentebalePAShe told Sky News: "There were board meetings where members of the executive team and external strategic advisors were sending me messages saying, 'Should I interrupt?', 'Should I stop this?' 'Oh my gosh, this is so bad'."
Dr Chandauka accused the prince of appointing a board member without consultation.
She described one instance where Harry announced a new appointment with immediate effect during a meeting, leaving everyone "shocked and quiet".
Dr Chandauka also detailed issues surrounding a polo fundraising event where Prince Harry wanted to bring a Netflix crew, causing the venue cost to increase, which she said resulted in the charity losing the venue for an event they were holding.
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Sentebale was established in 2006 by Prince Harry and Prince Seeiso of Lesotho in memory of their late mothers, Princess Diana and Queen Mother 'Mamohato Bereng SeeisoGettyShe claimed Meghan Markle unexpectedly attended with "a very famous friend," creating choreography problems on stage.
According to Dr Chandauka, Harry later asked her to issue a statement supporting Meghan after media coverage of the event, which she refused.
She stated: "We cannot be an extension of the Sussexes."
A source close to former trustees described her account of the polo match as "highly misleading" and denied all her allegations.