The environmental group says loopholes in the regulations mean many popular foods, including ice creams, chocolate bars and bread, could contain genetically-modified (GM) ingredients without being labelled.

The new regulations, negotiated during the UK's presidency of the European Union, require foods known to contain genetically modified ingredients to be labelled.

The former Agriculture Minister, Jack Cunningham, said at the time that the new regulations were "a triumph for consumer rights to better information."

Prince Charles: Concerned about "unforseen consequences" of GM food

However, they exempt foods containing soya oil or soya derivatives like lecathin, because they do not contain detectable amounts of modified DNA or protein.

Doctor John Fagan, an American biologist and a spokesman for Consumers' International - a coalition of more than 200 consumers' groups - says that as much as 70% of packaged food contains genetically altered ingredients, such as soya and canola oil.

In the US, GM soya beans were introduced in 1996 by Monsanto, and the EU approved their importation.

By the following year, they constituted around 15% of the approximately 60 million tonnes harvested.

American farmers mix GM soya with the rest of the harvest so it is effectively impossible to identify whether or not American soya beans have been genetically modified.

Soya beans are bought in huge quantities and traditionally food manufacturers purchase them as a commodity.

Iceland supermarket leads the way

Friends of the Earth is urging supermarkets and processed food makers to follow the lead of companies like the Iceland supermarket chain.

In March, it announced that all of its own-brand products would be free of GM ingredients by May.