A baker from Nice has launched a crusade to save France's "genuine" croissant from extinction amid claims that 85 per cent of the famous Gallic pastries bought in boulangeries are now "industrial".

Frédéric Roy, 46, who runs a humble bakery near the Riviera city's Promenade des anglais, struck a national chord after lamenting that the vast majority of croissants and pains au chocolat (chocolate pastries) sold in French boulangeries were, in his words, "de la merde" (crap).

"They barely look or taste like the real thing," he lamented. "A bad croissant gives a bad impression of our national heritage."

"I want the French to be able to buy a croissant knowing it is made with proper raw materials."