ONE of South Africa's biggest advertising agencies, McCann WorldGroup SA, continues to haemorrhage top executives amid concern about internal squabbles and that it is not serious about transformation.

At least six senior executives left the company within months of each other late last year, and now it has emerged that Laiza Zikalala, a senior black executive from its media-buying arm, Universtal McCann, is also leaving.

The latest resignation comes while the agency is involved in an acrimonious settlement negotiation with current CEO Reinher Behrens, whom it wants to step down.

Mr Behrens reportedly told the company he was treated unfairly and would not step down.

A board member said the standoff laid bare the tempestuous relationship between individuals at McCann SA and its American head office of McCann WorldGroup.

McCann SA said that it would not comment on specific resignations or "vague speculation and market mischief", but it admitted that it faced challenges.

Ms Zikalala is understood to be leaving because of the slow pace of transformation and infighting in the group. She declined to comment.

In November last year, the head of creative, Vanessa Pearson; the head of strategy, Rob van Rooyen; and the head of subsidiary McCann Erickson, Andrew Shuttleworth, resigned together to start their own agency.

A few months before them, business unit director Kumari Moodley, executive creative director Sandile Mkhasibe and traffic head Pauline Cindi also left the company.

The board member, who spoke on condition of anonymity, said the company was wracked by tension between the mother body, McCann WorldGroup, and McCann WorldGroup SA. He said this was also why Mr Behrens was under pressure to step down.

"Part of the problem is that McCann WorldGroup is a huge organisation, of which McCann WorldGroup SA is a small part. It is a very American organisation with a very American culture," the board member said.

McCann WorldGroup is part of the New York-listed Interpublic Group of Companies, which also owns such brands in South Africa as Draft FCB, Lowe Bull, Octagon and Webber Shandwick.

One former executive said part of the reason she left McCann SA was that the mother body had no respect for staff as individuals. "To most multinational agencies you are just a number. Everything is just about bottom line," she said.

Another executive who left the agency said the problems at McCann SA were industry-wide, especially in the multinational agencies. "The industry itself has been slow to transform and give black executives more scope. Why is a black executive good enough to bid for an account, but when the account is won then it is given to someone else to manage?"

McCann said it was committed to transformation and addressing issues it faced in a difficult market.

"While we are reluctant to discuss individuals or specifics - or to respond to vague speculation and market mischief - we can say that we are responding aggressively and creatively to the strategic challenges and opportunities inherent in the current environment," said Frasier Lamb, executive chairman of McCann SA.