Panacea Adviser has criticised advisers who promote their own business models by "knocking" others'.
Derek Bradley, chief executive of the adviser forum, claimed the practice of "comparative" advertising could generate complaints from both competitors and consumers when "sweeping, uncorroborated" statements are used to promote products and services.
In a recent blog post Mr Bradley wrote he has seen examples of financial advisers advertising their services in direct comparison with others in the market, such as promoting lower client-adviser ratios than competitors and claiming to save clients money by bringing investment management in-house, unlike others.
He said: "In my day to ‘big up’ your business by criticising you competitors was known as ‘knocking copy’.
"It was considered a no-go, not just with the ASA, FCA and FSA but also your fellow advisers.
"No-one should undermine another’s business model based on poor research or plain false assumptions just to promote your own."
Mr Bradley said any company making comparisons in marketing material should be able to verify statements and demonstrate claims are based on "reliable research and evidence".
He said: "You can promote your business far better by being very positive about your own firm without resorting to ‘knocking’ your competitors in such a blatant way.
"It looks unprofessional and almost certainly counterproductive. In other professions such copy could be grounds for a disciplinary hearing."
He added: "Suggesting you are the only honest fish in a sea of sharks does not give consumers confidence to join you in the water. We already have the regulator, ambulance chasers and the media talking advice down – we do not need to do it to each other."