Masterfoods was at the centre of a row in the UK earlier this year, when it emerged that it was replacing vegetarian-friendly whey in some of its products to one containing animal-derived rennet.
The confectionery giant performed a U-turn after it met with a volley of complaints from consumers and groups representing vegetarians.
The firm has said that the new scheme, which will feature the wording 'Suitable for Vegetarians' on the back of brands including Mars, Snickers, Galaxy and Malteser, is in response to the feedback it received.
It has used the Food Standards Agency's (FSA) guidance on vegetarian labelling as a benchmark for the process.
However the move is reigniting debate over how stringent such standards should be.
The Vegetarian Society has said that while it view's Masterfoods' move as "positive", it is withholding use of its iconic 'seedling' logo, recognised by vegetarian consumers as denoting suitable foods, since Mars bars are made with battery-farmed eggs.
"One of the criteria for the society's seedling symbol is that any eggs used in a product must be free range".
The FSA's vegetarian and vegan guidelines were drawn up in collaboration with The Vegetarian Society and The Vegan Society, as well as manufacturers and retailers.
They were released in spring 2006, but are not legally enforceable.
The FSA says the term 'vegetarian' "should not be applied to foods that are, or are made from or with the aid of products derived from animals that have died, have been slaughtered, or animals that die as a result of being eaten."
Its definition of animals is farmed, wild or domestic animals, including livestock poultry, game, fish, shellfish, crustacea, amphibians, tunicates, echinoderms, molluscs and insects.
A spokesperson for The Vegetarian Society told FoodNavigator.com that the guidance was conceived as a workable minimum which could be used if there should be a trading standard problem, for instance.
She called society's symbol the 'gold standard', but said that organisation would like the FSA to take on board the use of free-range eggs in its guidance.
Ideally and ultimately it would like a legal definition of vegetarian food to be put in place, but that is not likely to happen at least until the FSA has review the efficacy of the guidelines.
Managing director of Masterfoods' UK snack foods business said: "As a company, we believe in clear, transparent labelling and we are introducing this initiative because we want to communicate the suitability of our products to vegetarians."
Vegetarian Society chief executive Annette Pinner has signalled that the organisation is "happy to remain in dialogue with the manufacturer".
It has been estimated that there are 3.5 million vegetarians and 0.25 million vegans in the UK.