The IFA Association is fighting the Council of Mortgage Lenders' plans to set up a single industry-owned electronic trading platform.
Over 20 lenders are backing CML plans to have a trading system by September for intermediaries who want to process applications electronically.
Brokers will have to access the system through one "gateway" controlled by the CML.
The IFAA claims that the plans will give the CML a potential monopoly over electronic trading in mortgages.
It is concerned that a single CML gateway could be used to dictate which IFAs could and could not trade.
IFA Association chief executive Garry Heath says: "We are not happy with one gateway because it suggests a form of control. As independents, we do not like providers controlling us."
But CML head of external affairs Sue Anderson says: "It will have one access point because, from a security point of view, that is the least vulnerable. We are not trying to create a control but are seeing it as a way of streamlining business over the internet."