In a bid to reduce consumer confusion over labelling, the Food Standards Agency has proposed changes to its guidance on marketing terms used on supermarket own label premium range packaging.

Following a survey showing shoppers did not understand terms such as finest, quality, premium and selected, it has issued draft guidelines stating these terms should only be used if the product has been subjected to a "high level of quality control".

However, any labels using 'best' such as Morrisons' The Best and Somerfield's Best Ever would have to qualify whether it referred to the ingredients, the recipe, the brand or a range from a specific manufacturer.

"Tesco Finest can say 'we have a high level of quality control', but Morrisons and Somerfield may have to provide extra wording such as 'this product is made from the best ingredients," said Owen Warnock, food partner at law firm Eversheds.

Somerfield was adamant customers understood Best Ever. "There was ambiguity about our 'So Good' range, which is why we carried out research before introducing Best Ever," a spokesman said. "Shoppers opted for Best Ever as the message was self-explanatory. We would be happy to share our research with the FSA."

Although the FSA guidance is voluntary, a court would use the criteria to determine whether labelling was misleading.