Following a nine-month study, the Real Bread Campaign, which is part of the UK charity Sustain, found that only one supermarket chain was providing in-store ‘real bread' that met with their criteria.

The bread watchdog demands that authentic bread should only be made with flour, water, yeast, salt and only natural additional food ingredients like seeds, nuts, fats and fruit.

Processing aids and artificial additives are strictly prohibited.

Only Marks and Spencer loaves were found to meet the Real Bread Campaign's authentic bread criteria.

The report also found that many supermarket in-store bakeries do not produce fresh loaves baked on site but use bake-off or part-baked dough produced elsewhere.

This, claims the Real Bread Campaign, increases energy consumption two-fold.

Government cash incentives are granted to supermarkets whose in-store bakeries are classed as primary production sites.

But the watchdog believes that several supermarkets should not qualify and incentives should be granted only where the entire production is on site with an emphasis on using renewable energy sources.

In-store baked bread currently accounts for 17 per cent of UK bread purchases.

The Real Bread Campaign has also claimed that government regulations covering pre-packed and un-wrapped ingredients disclosure are in favour of the supermarkets rather than the customers.

According to the Food Labelling Regulations 1996, supermarkets are only required to show the presence of specific allergens and flour treatment agents, but not the name or composition of the agents, on labels and packaging.