The chair of a charity Prince Harry set up to help young people with HIV and AIDS in Lesotho and Botswana has accused him of “harassment and bullying at scale” after he quit this week over a dispute he described as “devastating”.

Harry, the younger son of King Charles, co-founded Sentebale in 2006 in honour of his late mother Princess Diana. He left it, along with co-founder Prince Seeiso of Lesotho and the board of trustees, following a dispute with chair Sophie Chandauka.

The royal family’s official website also mentions Harry’s work with the charity and it has yet to update the page with information about Harry’s resignation.

In an interview with Sky News, Chandauka said, referring to the way Harry resigned: “At some point on Tuesday, Prince Harry authorised the release of a damaging piece of news to the outside world without informing me or my country directors, or my executive director.”

“And can you imagine what that attack has done for me, on me and the 540 individuals in the Sentebale organisations and their family,” she said. “That is an example of harassment and bullying at scale.”