Completely removing GM ingredients from its own label ranges could take months if not years, the Co-operative Group has admitted.

The society, which this week said it would not plant genetically modified crops on its farmland, has also reiterated its commitment to taking GM out of its supply chain. However, sourcing non-GM
animal feed was proving difficult and time consuming, said head of Co-op brand and technical, David Croft.

“We’ve made a lot of headway on fish, poultry, eggs and pork, but when you are dealing with lots of smaller suppliers who buy seed from a myriad of local wholesalers, it’s harder.”

Likewise, milk was a particular problem as dairies did not generally segregate milk from cows fed on GM feed and those that weren’t before processing, he added.

News that Brazil - until the main source of non-GM soya - had recently approved the planting of GM crops in certain regions was another setback, admitted Croft.

Work was still progressing to provide alternatives to a rennet used in vegetarian cheese made from bacteria that had been genetically modified.

Greenpeace said supermarkets had done a lot of work to remove genetically modified animal feed from their meat supply chain, but dairy remained “a grey area”.