Bono has publicly apologised, following claims which surfaced today, that workers at the ONE charity, which he co-founded, were subjected to a culture of bullying and abuse.

The U2 singer, activist and philanthropist said that he was "furious" after the allegations originally surfaced in November of last year. Bono has clarified that he knew nothing about the allegations till then.

The U2 frontman did acknowledge, however, that the ONE organisation had failed to protect some employees at its Johannesburg office in South Africa. "I need to take some responsibility for that,” he said.

His comments came after the British newspaper, the Mail on Sunday, detailed a string of incidents, including allegations from a woman who says she was demoted after refusing to have sex with a Tanzanian MP.

"We are all deeply sorry. I hate bullying, can't stand it," he told the paper. "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."

Bono said that although the allegations focus on one individual, "the head office failed to protect those employees and I need to take some responsibility for that. In fact, if they would agree, I would like to meet them and apologise in person."

According to the Mail report, some former employees have launched legal action against the charity.

Gayle Smith, who has been the CEO of ONE since March last year, said an investigation found evidence of "unprofessional conduct" as well as "bullying and belittling of staff" between late 2011 and 2015.

"Staff were called names, and some said their manager put them to work on domestic tasks in her home," she said in a statement. "The investigation also found the situation was not adequately addressed nor resolved by executive management at the time, and that ONE's board was not, in my view, properly or fully informed."

Gayle Smith also confirmed that an allegation had been made that a woman was "demoted because she did not become intimate" with an official from another country. "We have not been able to corroborate these appalling claims,” she added. "We do not discount any allegation - we investigate them and will continue to do so should others arise."