Supporters of front-of-pack Guideline Daily Amount labelling have been given a major boost by a European Commission proposal to make the system mandatory across the EU.

In plans for a shake-up of food labelling, not yet published but seen by The Grocer, the Commission said the amount of energy, fat, saturates, sugar and salt in a product should be "included in the principal field of vision of the package" - effectively on the front of the pack.

The quantity of each nutrient in the product should also be "expressed as a percentage of the reference intakes", the Commission said.

The standard format for this would be for 100g or 100ml. However, where a food was sold in a single portion - such as a packet of crisps - it would be acceptable to express percentage reference intake on a portion basis. Percentages could also be expressed on a portion basis where the Commission had already agreed on a standard, guideline portion size for a product category.

This is good news for manufacturers of products eaten in much smaller portions than 100g. Breakfast cereal companies, who favour GDAs, are working on agreeing a standard portion size, which they will ask the Commission to accept as a guideline.

The Commission has also proposed making it compulsory to display the energy content of alcoholic drinks over 1.2% abv on pack. However, it is suggesting that unprocessed single ingredient foods, such as fruit and vegetables, should be exempt from the requirements.

Other exemptions include bottled water, tea, vinegar and single ingredient foods that have only been subject to smoking or maturing.

Although supporters of pure multiple traffic lights will be disappointed, the Commission's proposals do not necessarily mean the end of red lights on food and drink.

Provided food suppliers and retailers meet the legal obligations on labelling, they could be permitted to add extra information, such as traffic lights. These could be introduced via "soft law instruments, such as recommendations, guidance, standards or any other non-binding rules", but only after "sound consumer research" and "extensive consultation with a wide range of stakeholders".

The Food Standards Agency, which is about to begin a major research project into whether GDAs, traffic lights or a mix of the two is the most effective front-of-pack nutrition labelling system, declined to discuss the proposals.

A spokeswoman for the agency, which favours pure traffic lights, said: "We expect to see the proposal in December and will consider it carefully."

Jane Holdsworth, director of the GDA Campaign, which is backed by the Food and Drink Federation, said: "It's early days, but we're pleased the Commission appears to recognise the value of GDAs in terms of helping consumers understand food labelling."

The debate over front-of-pack nutrition labelling has divided the food industry, with Tesco and major manufacturers preferring pure GDAs while others, including Sainsbury's, have adopted the traffic lights approach. Asda has decided to use a hybrid approach, which combines both.