The poverty-fighting advocacy group founded by Bono and his U2 band mates is acknowledging “an institutional failure” after an internal probe uncovered an pattern of abuse and misconduct between 2011 and 2015 in the organization’s office in Johannesburg, South Africa.

Bono came out Sunday with an apology for the alleged behaviour by the charity.

“We are all deeply sorry. I hate bullying, can’t stand it,” Bono said to the Daily Mail. “The poorest people in the poorest places being bullied by their circumstance is the reason we set up One. So to discover last November that there were serious and multiple allegations of bullying in our office in Johannesburg left me and the One board reeling and furious.”

“The head office failed to protect those employees and I need to take some responsibility for that,” the singer added. “In fact, if they would agree, I would like to meet them and apologize in person.”

The One Campaign, which focuses on eradicating poverty and preventable diseases in Africa and other parts of the world, has shared the troubling results of its investigation, which found numerous examples of senior employees abusing staff.

RELATED: Bono Thinks ‘Music Has Gotten Very Girly’ And The Twitterverse Fires Back

In an open letter posted on its website, One Campaign CEO Gayle Smith said that staffers in the Johannesburg office experienced “bullying and belittling” by managers, with some employees telling investigators that one supervisor forced them work as party hostesses at her home on the weekends. The incidents, reported Smith, took place between late 2011 and early 2015.

In her letter, Smith also reveals an allegation from a female employee who says her superviser “made sexist and suggestive comments about her to a government official from another country,” while former employees alleged that the same woman “was demoted because she did not become intimate with the official.” However, Smith points out they have  “not been able to corroborate these appalling claims.”

RELATED: Bono Says ‘Poverty Is Sexist’ In New Op-Ed

“I want to say publicly and unequivocally — behaviour by any member of my team that undermines the dignity of others will not be tolerated,” writes Smith.

“We are only as good as our people and our values,” she continues, concluding by thanking the employees who came forward “to bring this to our attention and demand that we do better.”

Click to View Gallery
U2’s The Joshua Tree: A 30 Year Track-By-Track Lookback