The Queen and the Prince of Wales have been urged to strip Fortnum & Mason of its Royal Warrants because it sells foie gras.
Green MP Caroline Lucas accused the London store of touting the prestigious awards while "improperly" promoting the luxury pate to its customers.
She points to an investigation by the People for the Ethical Treatment of Animals (Peta) earlier this year that allegedly uncovered cruelty to geese at one of the store's French suppliers - claims Fortnum's said at the time it would investigate.
Fortnum's website states its foie gras is "produced by just two farms carefully selected for their excellent welfare standards".
Ms Lucas has written to the Lord Chamberlain calling for the two warrants the prestigious store holds not to be renewed.
She wrote: "Fortnum & Mason trades on its Englishness. It touts the Royal Warrants awarded to them. Its CSR (corporate social responsibility policy) talks of the store's high ethics and morals, particularly with regard to food production techniques and animal welfare.
"It states 'across everything Fortnum & Mason is and does runs its English character'.
"I am appalled that the mistreatment of geese and the sale of foie gras should be associated in any way with the essence of Englishness."
Foie gras force-feeding is outlawed in the UK, but the product is still available from fine food specialists and in restaurants.
Fortnum & Mason was granted a Royal Warrant by the Queen in 1955 with a second awarded by the Prince of Wales in 1996.
Royal Warrants last for five years and are reviewed by the Lord Chamberlain's Committee after four to assess whether they will be renewed but the royal household has the final say over which companies get the prestigious mark of recognition.
Ms Lucas added: "It is totally inappropriate for a Royal Warrant holder to sell a product that is illegal to produce in this country on cruelty-to-animals grounds and for them to promote the product within a framework that claims the highest animal welfare standards in the face of video documentation that belies that claim."
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