A group of disgruntled clients have accused Macquarie Group of fostering a toxic culture of harassment and predatory behaviour amid claims a male stockbroker cut off the ponytail of a female assistant and another adviser took "upskirting" photos of a colleague under her desk.

The allegations come amid a planned class action against the investment bank that accuses its brokers of deliberately ramping stock in Cleveland Mining Group by orchestrating the purchase of a Brazilian iron ore mine that was touted to be worth $34 billion, but never returned a dollar.

Last week, lawyers representing the investors sent a 26-page letter to Macquarie and the Australian Securities and Investments Commission that delivered a withering assessment of the bank's alpha-male culture and slack corporate governance.

"That culture led to a workplace defined by behaviour such as rampant drug taking leading to reckless trading after lunches, sexist and chauvinistic behaviour including an adviser engaging in predatory behaviour towards a female staff member and Macquarie choosing not to terminate that adviser because of the amount of commission the adviser earned," according to the letter from Macpherson Kelley Lawyers.

Several former Macquarie employees have told Fairfax Media that desk assistants were regularly preyed upon by several brokers, who were never held to account.

The brokers involved in the allegations have since left Macquarie, but continue to work in the finance industry.

Fairfax Media has been told one former Macquarie stockbroker used scissors to cut off a desk assistant's ponytail in 2013.

"He put the hair on her desk, right in front of her. She was so shocked she didn't say anything, and really only started talking about it at the Christmas party about a month later," said one source.

At least two staff complained about the attack to an office manager, but no disciplinary action was taken.

"Everyone was laughing about it, it was just a funny story to them. It was difficult to be a woman there and maintain a sense of respect. Particularly when no one had your back," said one former Macquarie staffer.

In 2010, the same broker was accused of stalking another female employee outside her home, but a subsequent complaint was said to have been ignored.

Another broker from the "millionaires factory" was accused of taking photographs on a mobile phone of a female manager in 2014 as she sat at her desk in the open-plan office on the 26th floor of 101 Collins Street.

The man responsible for the upskirting was asked to move desks, but again, no formal disciplinary action was taken.

Another female assistant, described as "voluptuous", was also secretly photographed by a former Macquarie adviser who then circulated the images on his phone.

"This is bullying, it's actually sexual assault, but no one had the courage to speak out, probably because they knew nothing would be done," one Macquarie source said.

A Macquarie spokeswoman said the bank treated all allegations of inappropriate or illegal behaviour seriously.

"You have raised serious and defamatory allegations of historic and inappropriate workplace behaviour, none of which involved current staff. The allegations were either never put to Macquarie, or those that were made were reviewed and appropriate action was taken," the spokeswoman said.

Macpherson Kelley Lawyers claimed in a letter to the corporate regulator that Macquarie's toxic culture had permeated every facet of the business.

"The above cultural matters go beyond just colour. The matters got to the very heart of of the lack of supervision within Macquarie's wealth division. It is no surprise that in a workplace that which tolerated such behaviour that trading patterns and conflict of interest reached unacceptable levels"

In June, Fairfax Media revealed two Macquarie Group executives repeatedly drugged a colleague with valium and laxatives during a business trip to South America.

Macquarie's then divisional director Michael Rosenbaum and investment adviser Stefan Whiting allegedly spiked the drinks of a male colleague as they travelled across Brazil and Chile to inspect gold mines owned by Cleveland.

Former Macquarie Bank investment advisers Stefan Whiting, left, and Michael Rosenbaum. Photo: Supplied

The 49-year-old victim has launched legal action against the investment bank, which was aware of the extraordinary allegations, but did not take any disciplinary action against the perpetrators.

Fairfax Media does not suggest Mr Rosenbaum or Mr Whiting were involved in any harassment of female staff at Macquarie. Both men left the bank in 2013.

But the pair have been accused of artificially inflating the price of Cleveland shares when they advised clients to buy the stock, according to the document sent to ASIC on behalf of disgruntled investors in the Perth-based company.

Macpherson Kelley Lawyers have alleged that Mr Whiting played a key role in the acquisition of a Brazilian iron-ore mine that helped the stock to almost triple in value to 95 cents between March and April 2012.

The share price collapsed in late 2012, before it was voluntarily suspended from the ASX in October 2016, when it traded at just 7 cents.

"Whiting was hopelessly conflicted... if Macquarie had had in place sufficient management and supervision, conflict of interest processes and Chinese walls, Whiting would have been sidelined from trading in CDG stock in September 2011, allowing clients to then receive independent and impartial advice," the letter by M+K Lawyers claims.

"Whiting exited himself from CDG in the first six months of 2013 whilst not disclosing to his clients that he was selling CDG shares."

Mr Rosenbaum purchased 480,164 Cleveland shares in the name of a company controlled by a relative, including 125,000 shares on April 3, 2012 - a day before a major ASX announcement by the Perth-based company.

It is also alleged that Mr Rosenbaum was able to protect about 15 of his wealthy clients by moving them out of Cleveland, when he learned the Brazilian iron-ore project known as Ferradura was a dud in late 2012.

At the same time, Mr Whiting was urging his clients to hold or buy more stock with repeated assurances it was destined to reach $1.20.

"At this time, there are two advisers sitting in the same office on the same floor and who are held by Macquarie as the lead advisers for Cleveland (one a divisional director) giving two polar opposite representations in relation to Cleveland," the letter states.

Former Macquarie adviser Stefan Whiting. Photo: Facebook

However, a Macquarie spokeswoman said an internal investigation had found no evidence of inappropriate trading.

"As part of a full investigation into this matter, we wrote in June to clients who owned shares in the relevant company, Cleveland Mining, informing them we are conducting a review. That investigation is substantially complete and we have found no evidence of inappropriate trading," the Macquarie spokeswoman said.

Macquarie accused Macpherson Kelley Lawyers of attempting to solicit clients for their class action, and warned they could be in breach of the Solicitors' Conduct Rules if they are unable to substantiate the allegations.

Mr Rosenbaum's lawyer, Arnold Bloch Leibler partner Leon Zwier denied his client had engaged in any illegal conduct when trading in Cleveland.

"Our client only trades based on publicly available information," Mr Zwier said.

Mr Whiting's lawyer, Genevieve Rock from Hall and Wilcox, also denied her client had engaged in any inappropriate or illegal trading activity.

Ms Rock provided a detailed response to questions from Fairfax Media, but insisted they not be published.

chouston@fairfaxmedia.com.au