The Co-op has been voted the UK’s leading retailer in a wide-ranging study of supermarket sustainability.

The Race to the Top survey looked at how supermarkets contribute to public health goals, treat workers, deal with farmers, promote animal welfare, support local economies, as well as issues of energy usage and waste management.

Other supermarkets to take part included Safeway and Somerfield. Asda, Tesco, Waitrose and Morrisons chose not to participate.

Deborah Doane of the New Economics Foundation said: “Supermarkets are now the main gatekeepers to the food system, with the top five now accounting for 70% of the food retail market.”

Head of brand and technical at the Co-op, David Croft, said that customers and shareholders of the major retailers should ask why they did not take part in the survey. “What have they to hide? No one retailer has all the answers, but by all working together on this iniative we can establish a framework of best practice.”

Doane added the unwillingness of many supermarkets to take part showed “a complete disregard for public concerns around sustainable development”.