Bell Pottinger chief executive James Henderson has resigned ahead of the publication of a critical report by Herbert Smith Freehills (HSF) into the PR giant's role in a controversial campaign in South Africa.

In the report, published today (4 September), HSF found that Bell Pottinger breached "relevant ethical principles" during its campaign work for the Guptas, an India-born South African business family, in 2016 and that the messaging was "potentially racially divisive and offensive".

HSF was commissioned by Henderson himself to undertake the probe in July.

The law firm was hired following accusations that month that Bell Pottinger had stoked racial tensions in South Africa during its work for Oakbay, the Gupta family's holding company.

Four Bell Pottinger staff members were dismissed or suspended earlier this summer as a result of the allegations, according to the Financial Times, ahead of Henderson's decision to step down.

HSF's report found that "certain material created for the campaign was negative or targeted towards wealthy white South African individuals or corporates and/or was potentially racially divisive and/or potentially offensive".

While Henderson and no other senior management figures were involved in the campaign, HSF's report adds that members of Bell Pottinger's senior management "should have known that the campaign was at risk of causing offence, including on grounds of race".

In a statement today, Henderson said: "Having read these findings, I recognise the business requires a change of leadership to fix the problems of the past and to move forward. Although I neither initiated nor was involved in the Oakbay work, I accept that as CEO, I have ultimate executive responsibility for Bell Pottinger.

"I feel deeply let down by the colleagues who misled me. However, I think it is important I take proper accountability for what has happened."

Bell Pottinger said that while it does not believe that HSF's findings are "representative of the way it works in general", it is "determined to learn lessons from this review" and "take appropriate action".

Earlier this year, the PR company announced plans to introduce new measures, including clearer staff training and committee reviews of work.

Previously, the Public Relations and Communications Association, launched its own investigation into Bell Pottinger after South Africa's main political opposition party, the Democratic Alliance, brought a complaint against the agency.

HSF declined to comment.