Progressive managing director Dave Chambers yesterday confirmed that his company would not be going this year.
"We continue to engage with the FGC on industry topics such as food safety; we just aren't attending the conference.
"Given the high-profile role FGC has played in making public allegations about our business over the last six months, it would be inappropriate for our company to attend this year's conference.
"We greatly value our supplier relationships and our priority is to continue to work directly with our suppliers to advance our business and theirs."
FGC chief executive Katherine Rich told the Weekend Herald her organisation did not initiate the investigation "and we don't have any control or influence over the Commerce Commission".
She said some of her members "have reported an improvement in their dealings" with Progressive.
Labour's commerce spokesman, Clayton Cosgrove, said he questioned why Progressive was "adopting such a hostile tactic to an industry association whose duty is to represent its members and which is doing just that. Whether they're reflecting what Progressive would like is an irrelevancy."
A spokeswoman for Progressive yesterday said: "Just to be clear, we are co-operating with the Commerce Commission and we support any of our suppliers who are contacted to do the same, and always have."