Peta has exclusively revealed to IBTimes UK that actor Ralph Fiennes has written to Fortnum & Mason chief executive Ewan Venters to complain about its sale of foie gras.
Fiennes said he was appalled that the exclusive department store sells the product after seeing a video of geese being force-fed to produce the delicacy.
The actor urged Venters to ask him to stop selling foie gras, which is illegal to make in the UK.
An undercover film by People for the Ethical Treatment of Animals (Peta) exposed the abuse suffered by geese at a farm that supplies Fortnum & Mason with foie gras.
The film, narrated by Roger Moore, shows the birds being force-fed and having knives plunged into their throats without being stunned.
The geese are fed huge amounts of grain which is pumped into their stomachs through metal pipes, causing their livers to swell to 10 times their normal size and press up against their lungs.
In his letter, Fiennes said: "Animals and their welfare mean a lot to me and to the majority of the British public. That's why after watching video footage from Peta's harrowing undercover investigation of goose farms from which Fortnum & Mason obtains foie gras, I had to write to you.
"I'm sure that anyone who has watched the distressing footage - which shows intelligent, gentle birds condemned to spending the last weeks of their lives in small barren pens, forced to stand 24 hours a day on metal grating with their waste left to collect below - could not fail to be appalled.
"A product that causes so much suffering that's illegal to produce in the UK should not be sold in an iconic British department store like Fortnum & Mason. As managing director, you have the power to end the company's involvement in this cruelty."
On its website, Fortnum & Mason says: "Fortnum's foie gras is produced by just two farms carefully selected for their excellent welfare standards. It is the ultimate luxury for any time of year."
A statement from the copmay said: "
"Foie gras is sold in shops throughout the UK, and is used in many top restaurants. We do understand that it is not to some people's taste, and we respect their right to make their feelings known. However, foie gras has been on sale at Fortnum's down the centuries, and a sizeable number of our customers enjoy it. We believe they should have the freedom to choose whether to buy it or not."
Because of its continued sale of foie gras, Peta named Fortnum & Mason the "cruellest retailer" in its Food and Drink Awards in May.