The FSA said on Tuesday it had researched claims by Friends of the Earth that gene-modified (GM) ingredients were used in tortilla chips on sale at supermarkets in Britain, where officials are still testing whether to grow GM crops.

The government agency said levels of GM material in the chips were "far too low to pose a danger to human health", but the environmental group said the agency was not equipped to decide what affect the GM ingredients would have.

"We are extremely disappointed that the FSA has chosen to use the BSE approach: claim its safe first, investigate the problem later," Adrian Bebb, a campaigner from Friends of the Earth, said in a reference to the  previous UK government's early statements about mad cow disease.

Bebb added, "How can the FSA be so sure that small quantities of GM ingredients are safe when they haven't been authorised for sale in Europe? The presence of illegal GM ingredients at any level points to huge holes in the system to protect consumers."

Public opinion in Britain has turned against GM food, with many shops and restaurants advertising that they do not sell GM food.

Friends of the Earth earlier this month said it had found GM maize in samples from Sainsbury's , Tesco and Asda own-brand tortilla chips as well as those produced by Phileas Fogg. The GM maize varieties were said to have been produced by biotechnology company Monsanto, which swiftly challenged the group to reveal evidence to back the claims.