U2 frontman Bono has issued an apology after Johannesburg workers at his ONE charity came forward with claims of a culture permeated with abuse and bullying. 

Allegations were first published in The Mail on Sunday, prompting the singer to immediately release a public apology.

The Dublin-born singer said he was "deeply sorry" and "furious" over workers' reports of inadequate and unfair treatment by managers at their South African office from 2011 to 2015. 

Allegations made in The Mail included one from a married woman who claimed she was demoted from her position at ONE after refusing to have sex with a Tanzanian member of parliament.

Other staff members told they had been made to do domestic work at a manager’s house.

This is how we celebrate the possibilities if leaders invest more in education of girls and women in Senegal! #InternationalWomensDay #IWD2018 pic.twitter.com/xqGxuVl9SQ

— ONE (@ONEinAfrica) March 8, 2018

The Mail also claimed that ONE had failed to pay South African taxes and was employing illegal foreign workers.

Bono, real name Paul Hewson, founded ONE in 2004 as a non-governmental organization with a bid to campaign towards a world free from extreme poverty and preventable disease.

Read More: Bono on equality: nowhere on earth do women have the same opportunities as men 

The 57-year-old rocker has also pledged to meet victims to apologize in person.

"We are all deeply sorry. I hate bullying, can't stand it," his statement added.

These strong girls just shared their stories on challenges they have experienced in assessing and staying in school in Senegal at our ONE #internationalwomensday dialogue in Dakar. pic.twitter.com/k4lzJ29YrP

— ONE (@ONEinAfrica) March 8, 2018

"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 and his wife Ali Hewson

Bono and his wife Ali Hewson

The singer added that he will be taking "some responsibility" for that. 

According to Agence France-Presse, lawyers acting for seven former staff members of the NGO have launched a compensation case, seeking damages for "emotional, physical and psychological abuse".

The New York Times adds that former employees are seeking up to $5 million in damages. 

November 14, 2012 - Singer and activist Bono and World Bank President Jim Yong Kim discuss solutions and actions needed to end extreme poverty.Flickr