A raft of heavyweight clients including HSBC and EY together with a key investor have abandoned under-fire Bell Pottinger amid a storm of criticism over a campaign it ran in South Africa accused of stoking racial tensions.

It came as the City communications firm hired accountancy firm BDO to advise it on its options, understood to include a potential sale. Senior departures are also expected, with John Sunnucks, the chairman of Bell Pottinger’s corporate and financial practice, the most high profile so far.

The firm has been fighting to salvage its own reputation this week after being kicked out of Britain’s PR trade body for bringing the profession “into disrepute” and losing its chief executive James Henderson.

The fallout is from work Bell Pottinger undertook for billionaire family the Guptas that included a campaign that targeted wealthy white South African business rivals to allegedly deflect attention from the Guptas’ close links to president Jacob Zuma.

An independent report by law firm Herbert Smith Freehills, commissioned by Bell Pottinger, found top managers mishandled the work, which included content it deemed unethical and likely racially divisive and offensive.