The Food Standards Agency has decided to show its first television advertisement promoting its traffic light food labelling system in a bid to tackle the obesity crisis in Britain.

The publicity could isolate Tesco and Morrisons, who have continued to use their own labelling systems, from retailers who have adopted the scheme Sainsbury’s, Waitrose, Asda and Co-op.

The commercial, which uses the slogan “High, medium and low - be in the know”, shows the red, amber and green symbols that inform consumers of the amount of salt, sugar, fat and saturated fat in food items.

Tesco said last night that it had introduced new health warning labels on packs. The spokesman added: “With 3,500 products already labelled, we have gone further, faster than any other retailer to provide nutritional information.”