The warning comes as superannuation groups across the Tasman call for the ban on commissions for financial planners in Australia to be extended to existing clients.

Although it is considered unlikely the Aussie commission ban will be copied here, there is a possibility it could be looked at during later rounds of the on-going process of regulating New Zealand's financial markets.

Thomas, who is on the board of the Financial Markets Authority, told Good Returns that in her personal opinion as a fund manager, banning commissions would probably do more harm than good.

"In my view banning commissions in New Zealand would remove a number of smaller, independent players from the market," she said.

This would be bad news for consumers, as it would make it more difficult and expensive to get financial advice.

"I think the unintended consequence would be that no-one would have anywhere to go for financial advice.  It would be totally counter-productive to go down that particular path."

It would also make it harder for smaller, boutique fund managers to distribute their products and would give a big advantage to large organisations with tied adviser forces, Thomas said.

Instead of banning commissions, she said there needed to be a focus on two key aspects of commissions: firstly, disclosure and secondly, hidden incentives that she said bias advisers away from clients' best interests.

"Lots of people don't mind the fact their adviser is taking a commission as long as they know what it is and who it is paid by.

"In the UK I have an adviser who is paid on commission - I had a choice between a fee and commission and I chose commission.  I know what the commission is, where it's going and what it's paying for."