Duncan Swift, head of Grant Thornton's Food and Agribusiness Recovery Group, said that the supermarket buyers' unreasonable behaviour was a major factor in financial distress among the UK's food producers.
He gave examples of tactics used by the multiples, including retrospective discounts, supplier contributions, extended credit terms and short-notice de-listing.
"They have convinced politicians that regulation of the supply chain would increase the cost to the consumer," he said.
He alleged that the OFT had "decided to be blind" when looking at 500 relationships between suppliers and retailers and finding no cause for action, but ignoring failed relationships.
Swift said the Competition Commission had "set a task too far" as it had no power to impose its findings. He urged wholesalers and suppliers to act responsibly and inform the FWD of suppliers who indulged in shady deals, and called for ideas on ways in which an industry ombudsman could be funded.