The UK's four biggest supermarkets are bad for business, consumers and the environment, environmental action group Friends of the Earth has said.
The supermarkets have been attacked on a number of issues
In the latest of numerous attacks on supermarkets, the action group will put its views to MPs on Thursday, the day before Tesco's annual general meeting.
The campaign group wants stricter regulation of the supermarkets.
Supermarkets have long argued they are simply giving UK consumers what they want and treat suppliers fairly.
The action group also claims that farmers and suppliers in the developing world are not getting a fair deal because of the purchasing power of Tesco, Asda, Sainsbury's and Morrisons.
Friends of the Earth says more regulation is needed to stop the suffering of UK farmers and smaller High Street retailers.
"MPs must act now to curb the growing market power of supermarkets and ensure that Britain's booming supermarket industry does not kill off farmers, consumer choice and the traditional British High Street," said Friends of the Earth's supermarket campaigner Vicki Hird.