Bono has apologised after claims were made that workers at a charity he co-founded were subjected to bullying, verbal abuse and sexual harassment over a four-year period

The U2 singer, 57, said he was “furious” after the allegations surfaced in November last year. He admitted the One organisation, created in 2004 to fight extreme poverty and preventable diseases, failed to protect some employees at its Johannesburg office in South Africa and said: “I need to take some responsibility for that.”

“We are all deeply sorry. I hate bullying, can't stand it,” he told the Mail on Sunday. “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 added that he would like to meet the victims to apologise in person.

The former employees at the One Campaign claimed they were bullied by a senior official at its Johannesburg office for almost four years, tweeting their allegations of misconduct and claiming some staff in Africa were “treated worse than dogs”.

In an investigation reported by the Daily Mail, the group alleged that between 2011 and 2015 they were verbally abused and told by a supervisor to do domestic work at her home during weekends.

One woman alleged that she was demoted after refusing to have an intimate relationship with a foreign government official, after her manager made “sexist and suggestive comments” about her to him.

The allegations were revealed in a letter to members from Gayle Smith, who became One’s chief executive in March 2017. She said One had filed a serious incident report to the Charity Commission earlier this month.

The inquiry found that a former official subjected junior employees to “verbal or email statements such as calling individuals ‘worthless’, ‘stupid’ and an ‘idiot’, at times doing so in front of third parties,” One said.

Smith said the campaign had not been able to corroborate the claims by the female employee who said she been demoted for not becoming intimate with the foreign official, but added: “We do not discount any allegation – we investigate them and will continue to do so should others arise.”