The Soil Association has urged retailers not to relax their rules on GM feed, warning this would further undermine public trust in animal products following the horsemeat scandal.

The move comes after egg producers called on supermarkets to stop requiring producers to use only non-GM feed because non-GM soya was becoming increasingly expensive and difficult to source.

In a joint letter to the British Retail Consortium, the Soil Association, Friends of the Earth, GM Freeze, GMWatch and Gene Watch UK warned such a relaxation of the rules would be unwise, especially if the use of GM feed would not end up being highlighted on product labels.

“We believe, particularly in the wake of the scandal about unlabelled and unlisted ingredients in beef burgers, that this would be a very serious mistake, further undermining public trust in animal products sold by British supermarkets,” they wrote. “The public concern about the presence of horse and pork DNA in beef burgers indicates what we are sure your members already know, namely that their customers rely on them to ensure the integrity of the products they sell.”

The letter also challenged egg producers’ claims that non-GM soya was becoming difficult to source, arguing imports of non-GM soya to the EU were actually increasing in response to supermarkets in other European countries – such as Carrefour in France – had committed to using only non-GM feed.

It also said a recent joint Defra and industry project had suggested UK-grown peas and beans could “probably replace most, if not all, imported soya in chicken diets with little or no impact on production” – although it conceded the project was yet to be trialled on farms.

“We hope that the British Retail Consortium and your members will, first and foremost, listen to the views of your customers, and move quickly to avoid all use of GM soya and other GM feed crops in farm animal feed, unless the resulting products are clearly labelled as coming from animals fed on GM,” the letter added.