FFA called on Thursday for formal expressions of interest (EOI) from potential bidders, who have been asked to provide information about their strategy for a new club and to prove their financial bona fides.

The governing body aims to announce by the end of October which two new clubs - expected to be from Sydney, Melbourne or Brisbane - will be granted entry to the competition for the 2019-20 season.

But in finally starting the formal expansion process, FFA has once more drawn the ire of the existing clubs and their representative, former Adelaide United chairman Greg Griffin, the chairman of the Australian Professional Football Clubs Association (APFCA).

Griffin wrote to FFA chief executive David Gallop to warn their expansion plans were in "complete conflict" with the ongoing governance reform process being steered by FIFA.

"(This) process has been undertaken without any formal consultation of both the (clubs) and the PFA," wrote Griffin, who sold his share in Adelaide this month but remains at the helm of APFCA.

"Should you proceed to make the announcements that you seemingly intend to make soon, APFCA puts you on notice that it does not accept the legitimacy of the process, whatever that may have been, adopted by FFA Administration and the FFA Board to expand the A-League competition.

"Unless and until the corporate governance issues have been resolved any decision made by the FFA Board as to expansion lacks all legitimacy and will not be accepted by APFCA."

FFA's announcement did indicate that existing clubs, state federations and the players union will be given the chance to submit their views on expansion and how new teams would affect their operations.

However, Griffin said that was contrary to the agreement made by stakeholders last month to wait for news from FIFA and AFC as to how the "Congress Working Review Group" would be structured.

"We have done a lot of work on the fundamentals behind successful expansion of the A-League and we are confident that we will receive some high-quality bids as part of this process," Gallop said.

Once it has received all EOIs, FFA intends to select a short-list of bidders and request from them a fully fledged proposal by the end of August.