The distinctive heart-shaped golden case, which narrowly escaped being melted down after the French Revolution, was stolen overnight from the Musée Dobrée in the west of France on Friday.

Catherine Touchefeu, a local councillor in Nantes, told The Local: “If by any chance the thieves were motivated by the fact that it is shiny and made of gold, they should understand that its historical and symbolic value far outweighs its 100 grams of gold.”

Philippe Grosvalet, president of the Loire-Atlantique department, added: “These burglars have attacked our common heritage.

“Much more than merely a symbol, Anne de Bretagne’s heart belongs to our shared history. Queen Anne, Duchess of Brittany, had wished that her heart be buried with her parents.”