A “devastated” Prince Harry has reportedly quit the 20-year-old children’s charity he co-founded in his mother’s memory amid a heated internal dispute.

The Duke of Sussex’s decision to depart Sentebale came with relationships within the organisation “broken down beyond repair”, according to a leaked statement.

Harry and Lesotho’s Prince Seeiso founded the African children’s charity in 2006, after the duke spent two months in the southern African nation on a gap year in 2004.

Sentebale was to help vulnerable children in Lesotho and Botswana who have been affected by poverty and HIV/Aids.

Both princes were inspired by the work of their late mothers. (“Sentebale” means forget-me-not in the local Sesotho language – the flowers were apparently a favourite of the late Diana, Princess of Wales.)

“The charity symbolises our pledge to always remember and advocate for the most vulnerable among us,” Harry once said.

But Britain’s Times newspaper reported on Tuesday (local time) that Harry and Seeiso had walked away, amid “unthinkable” infighting between Sentebale chairwoman Dr Sophie Chandauka and its board of trustees.

“With heavy hearts, we have resigned from our roles as patrons of the organisation until further notice, in support of and solidarity with the board of trustees who have had to do the same,” they wrote in a joint statement leaked to the paper.

“It is devastating that the relationship between the charity’s trustees and the chair of the board broke down beyond repair, creating an untenable situation.”

While details of the dispute remain unclear, it is reportedly due to a decision to focus fundraising in Africa. The Times reports that Sentebale is the subject of a Charity Commission investigation.

“What’s transpired is unthinkable,” the princes’ statement said.

“We are in shock that we have to do this, but we have a continued responsibility to Sentebale’s beneficiaries, so we will be sharing all of our concerns with the Charity Commission as to how this came about.”

Chandauka, a Zimbabwe-born lawyer who was appointed to her position last year, released her own statement.

“For me, this is not a vanity project from which I can resign when I am called to account,” she said.

She said she had reported the trustees to the Charity Commission and that a British court had issued an injunction to stop them removing her.

“There are people in this world who behave as though they are above the law and mistreat people, and then play the victim card and use the very press they disdain to harm people who have the courage to challenge their conduct,” Chandauka said.

She said it was a “story of a woman who dared to blow the whistle about issues of poor governance, weak executive management, abuse of power, bullying, harassment, misogyny, misogynoir – and the cover-up that ensued”.

Prince Harry and Sentebale chair Sophie Chandauka at a charity polo fundraiser in Florida last year. Photo: AAP

Sentebale’s five former trustees include Mark Dyer, a lifelong friend of Harry and former equerry to the King. The group said it was “devastating” to have to resign but they had lost “trust and confidence in the chair of the board”.

“We are deeply proud to have supported the visionary work of the founding patrons Prince Seeiso and Prince Harry, who founded Sentebale in memory of their mothers,” a joint statement said.

“For two decades, Sentebale has championed hundreds of thousands of children and young people, providing them with care, training and life skills, which not only benefit each individual child they support, but their families and their communities as a whole.”