France’s Camembert war has reignited after protesters kicked up a stink over proposed changes to labelling rules.

Campaigners say the move to allow mass-produced Camembert to use the prestigious appellation d’origine protegée (AOP), or protected designation of origin, label was an attack on the country’s cultural and gastronomic heritage.

They protested on Wednesday outside the Assemblée Nationale and posted cheeses in MPs’ letterboxes.

Camembert de Normandie AOP is made by a specific process with precise ingredients, including unpasteurised milk, half of which must come from Normandy cows raised in a defined area in the Normandy region. Only 5,000 tonnes of Camembert de Normandie AOP are produced each year.

Cheeses in MPs’ letterboxes at the National Assembly. Photograph: Gonzalo Fuentes/Reuters

The protesters say the traditional Camembert is about to be swallowed up by its factory produced rival Camembert fabriqué en Normandy, or Camembert made in Normandy, which from 2021 will also be allowed to use the AOP label. It is made from pasteurised milk from any cow breed raised anywhere.

Around 60,000 tonnes of this type of Camembert are produced each year, and it is the one you are most likely to find in your local supermarket.

Véronique Richez-Lerouge, the president of the Association Fromages de Terroirs, or the Cheeses of the Land Association, , whose members protested outside the French parliament on Wednesday, said allowing the industrially produced Camembert to carry the AOP label was “opening a Pandora’s box”.

“The AOP system was created to protect products from being copied. What is now happening is the inverse,” Richez-Lerouge said. “We are talking about tradition, heritage and image. Camembert de Normandie AOP and Camembert fabriqué en Normandie are not the same thing at all.”

The French deputy Richard Ramos and Veronique Richez-Lerouge, pictured on the boxes of cheese used in the protest. Photograph: Gonzalo Fuentes/Reuters

Richez-Lerouge says the move is a victory for the industrial food lobby and what she calls “widespread paranoia” about raw milk. She hopes to recruit Prince Charles to her campaign. The Prince visited the COP21 global climate conference in Paris in 2015, and said the survival of cheeses made in the traditional way with unpasteurised milk was threatened by “bacteriological correctness”.

His remarks followed research that showed only around 10% of the cheeseconsumed in France was made with unpasteurised milk, and that consumption was falling by 4% a year.

The cheese war began 21 years ago, when the Normandy Camembert made from unpasteurised milk first obtained its AOP, a designation recognised at the EU level.

Producers of both types of Camembert agreed last year to share the AOP in a compromise under which the industrial producers agreed to use only milk from herds with at least 30 percent Normandy cows as of 2021.

Patrice Chassard, the president of the French AOP cheesemakers’ national committee, who arbitrated the controversial deal, said allowing both to use the AOP label would boost raw milk production. “It will put Normandy cows back into the Normandy pastures,” he told Agence France-Presse at the time.

The deal, however, is not to Richez-Lerouge’s taste. She says authorising the use of heat-treated milk for all AOP Camembert is choosing quantity over quality and risks the famous cheese “sinking inexorably into mediocrity”.

“The Camembert de Normandie is a symbol of our country and cheese, but it will be killed off if we let them pasteurise it in 2021,” she said. “Nine out of 10 AOP Camemberts will be pasteurised and industrial, made in a production line, like vulgar products.”

It is a row as French as berets, baguettes and, well, Camembert.