Farmers are the weakest link in the food supply chain and are suffering, according to National Farmers' Union president Meurig Raymond.
Mr Raymond was speaking at the Forum for a Better Functioning Food Supply Chain, which is jointly chaired by EU agriculture commissioner Phil Hogan.
The NFU president said farmers cannot endure the suffering any longer and a cultural change in business ethics is needed.
"We can no longer accept that those misbehaving stand to gain financially from their actions," he said.
"Purely voluntary schemes to curb unfair trading practices, such as we had in the UK, did not work and we ended up with legislation – the GSCOP – and a Groceries Code Adjudicator – as the tools to solve this problem.
"EU agricultural cooperative Copa could not agree with the other stakeholders on a purely voluntary framework to implement and enforce these principles of good practice. Experience has shown us, in various Member States that a voluntary only system does not work.
"That is the reason why several Member States – currently 20 of them – have or are about to adopt legislation aimed at curbing unfair trading practices and improving the functioning of the food chain.
"They are also looking at robust enforcement mechanisms based on an independent third party adjudicator that can receive and act upon anonymous complaints as well as applying sanctions when rules are breached.
Mr Raymond said a competitive food supply chain in the EU can only be achieved if all of the links are sustainable in three dimensions: economic, social and environmental.
"Farmers need to receive fair prices for their produce and work together with their cooperatives and other processing companies to produce high quality, high value, nutritious food for the consumers both in the EU and in Third Countries. This cannot be done without research, innovation and, most of all, the involvement of all links in the food chain."
