Slaters alleges that Bell Potter advised clients to buy stock in a share offer by Brisbane biotech company Progen Pharmaceuticals - a share offer it was partly underwriting. The firm claims Bell Potter didn't disclose the conflict appropriately to the clients.

According to the firm, as many as 120 Bell Potter retail clients purchased some $28 million of PGL stock.

So far 35 former Bell Potter clients have joined the litigation which is being funded by litigation funding company Litigation Lending Services. Slaters is preparing to lodge a statement of claim in the Federal Court within three weeks.