The nation’s competition regulator says fruit and vegetable growers are wearing almost all the downside in the sales agreements they strike with the supermarket giants, with major farming groups warning of long-term consequences for food production if the imbalance is not fixed.

In a 441-page report issued on Friday, the Australian Competition and Consumer Commission described the relationship between food growers and the two biggest supermarket chains, Woolworths and Coles, as one of “one-way accountability” and marked by fears of retribution.