Bell Pottinger, the public relations company founded by Margaret Thatcher’s spin doctor Lord Bell, will on Friday be hauled before the public relations and communications association (PRCA) disciplinary committee over allegations it ran a secret campaign to stir up racial tension in South Africa on behalf of billionaire clients.

Mmusi Maimane, leader of South Africa’s opposition Democratic Alliance party, has demanded that the British PR industry body censures Bell Pottinger for running a “hateful and divisive campaign to divide South Africa along the lines of race”.

Bell Pottinger is accused of seeking to stir up anger about “white monopoly capital” and the “economic apartheid” in the country to draw attention away from the wealthy and controversial Gupta family, who are accused of exploiting their friendship with President Jacob Zuma to extract billions of dollars from the state. Bell Pottinger, which was being paid £100,000 a month by the Guptas’s Oakbay company, allegedly orchestrated the creation of fake Twitter accounts to target prominent white business people in South Africa, some of whom were Bell Pottinger clients.

Maimane, who this week called an unsuccessful vote of no confidence in Zuma over allegations that he gave the Guptas’ companies preferential access to government contracts, has called for the PRCA to strip Bell Pottinger of its membership of the trade body. He has also called on the Chartered Institute of Public Relations (CIPR) to also investigate Bell Pottinger’s work in South Africa, which has led to protests outside the firm’s offices and a social media campaign using the hashtag #bellpottingermustfall.

“Bell Pottinger must face consequences for their collusion with the Guptas using a hateful and divisive campaign to divide South Africans along the lines of race. This was coordinated campaign to further Gupta financial interests‚ and ensure the captured ANC continued to provide lucrative contracts that lined Gupta pockets,” Maimane said. “South Africa is not a political playground where international corporations can disregard ethics to turn a profit. Bell Pottinger’s unethical compliance in these projects is unacceptable and the Democratic Alliance has taken steps to ensure they are held to account.”

Maimane had called on the PRCA to open the hearing to the public, but Bell Pottinger has invoked its right for the hearing to be held behind closed doors.

Bell Pottinger’s role in the scandal, which was revealed in more than 100,000 leaked emails dubbed the GuptaLeaks, has thrown the PR company, founded in 1987, into crisis.

The company’s chief executive, James Henderson, has issued what he describes as an “unequivocal” apology and fired Victoria Geoghegan, the partner leading the Gupta account, and suspended three other staff for the “inappropriate and offensive” social media campaign.

“Much of what has been alleged about our work is, we believe, not true – but enough of it is to be of deep concern,” he said “We wish to issue a full, unequivocal and absolute apology to anyone impacted. These activities should never have been undertaken. We are deeply sorry that this happened.”

Henderson, who declined to elaborate on his public statements to the Guardian, has appointed City law firm Herbert Smith Freehills to investigate the allegations and has said it will publish the report. The contract with the Guptas, who own a mining-to-media conglomerate, was cancelled in April.

Henderson said he and other senior managers were “misled” about the activities being carried out in South Africa, but Tim Bell, who quit the firm last year in part because of concerns about working for the Guptas, said he had raised concerns with the company’s ethics committee.

Bell, who has previously represented the Pinochet Foundation, Syrian first lady Asma al-Assad and the governments of Bahrain and Egypt, told the BBC that working for the Guptas was a “politically toxic contract” and the firm should walk away. He warned that it could lose other clients.

Bell Pottinger has lost some of its biggest clients, including South African investment bank Investec, the South African tourism board, London-listed African-focused miner Acacia and Richemont, the luxury goods company that owns Cartier and Montblanc and which is controlled by South African billionaire Johann Rupert.

Rupert reportedly told the annual meeting of his holding company Remgro that Bell Pottinger had arranged for him to be targeted as part of the social campaign against “white monopoly capital”.

“And whilst they were still in the employment of Richemont, they started working for the Guptas. The very same person … Their total task was to deflect attention [from state capture allegations involving the Guptas]. Guess who they took as a target? A client of theirs – Me!”

Rupert said Bell Pottinger’s contract with Richemont was cancelled after 15 to 18 years.

As well as pressing for industry sanctions against Bell Pottinger, Maimane has written to a host of the PR firm’s biggest clients calling on them to drop the agency. “Though legal action is effective‚ corporations respond to their bottom line faster than they do to judges‚” he said.

Danny Rogers, editor-in-chief of PR Week, said it was shocking that Bell Pottinger had once again allowed itself to become the story following a 2011 investigation by the Independent into the firms alleged “dark arts” used to improve companies’ reputations. Those revelations also led to a PRCA hearing, which did not censure Bell Pottinger.

“The word in the PR industry is that clients are very uneasy and more are considering leaving,” Rogers said. “Clients do not want to be represented by PR firms that become the story or are associated with scandal. And this has been a huge scandal that has damaged the reputation of political consultancies.”

Rogers said it was rare for a PR firm as big as Bell Pottinger to be hauled before the PRCA and said he could not recall any big companies ever being disbarred from the association. “It would be quite a big deal if they got thrown out.”

However, he said the industry “needs to take a stand” and “show that these practices are not endemic and that the PR industry as a whole believes in open, transparent and ethical communications”.

• This article was amended on Sunday 13 August to remove a picture.

