The Charity Commission has opened a compliance case into a charity co-founded by the Duke of Sussex after its chair reported trustees to the regulator amid an extraordinary row.

The regulator said it was looking into Sentebale, a charity Prince Harry co-founded with Prince Seeiso of Lesotho in 2006 to help people in Africa living with HIV and Aids.

Prince Harry stepped down as the charity’s patron citing the relationship between chair Sophie Chandauka and trustees, which the duke said had “broken down beyond repair”.

Chandauka took legal action against the charity and reported its trustees to the Charity Commission after being asked by the board to step down.

In a statement, she alleged there was “poor governance, weak executive management, abuse of power, bullying, harassment, misogyny and misogynoir” at the charity.

The regulator said today that after a period of assessing the initial concerns, it had told the charity on 2 April it had opened a regulatory compliance case.

The commission said it was in direct contact with parties who had raised concerns to gather evidence and assess the compliance of the charity and trustees with their legal duties.

It said its focus would be to determine whether the Sentebale’s current and former trustees, including its chair, had fulfilled their duties and responsibilities under charity law.

In a statement, Chandauka said she welcomed the regulator’s investigation.

“For completeness, I should mention that we initiated an internal governance review last year, the findings of which we will share with the Charity Commission,” she said.

“We hope that, together, these actions will give the general public, our colleagues, partners, supporters, donors and the communities we serve comfort that Sentebale and its new board of trustees are acting appropriately to demonstrate and ensure good governance and a healthy culture for Sentebale to thrive.

“We appreciate the patience, understanding and tremendous support we have received from our existing and prospective partners and supporters, and look forward to continuing to work together with you as we recalibrate for an ambitious future.”

Carmel Gaillard, executive director of Sentebale, said transparency and accountability were central to how the charity operated.

“As executive director, I speak on behalf of the Sentebale executive team and operational staff that we welcome the clarity this process will bring,” Gaillard said.

“The executive team and I are fully committed to supporting the Charity Commission’s regulatory compliance case in any way needed.

“We will also continue to work closely with the chair and the new board of trustees to ensure the smooth running of the organisation, keeping our focus firmly on delivering for the young people and communities we serve.”

The Duke of Sussex has been contacted for comment.