Animal rights campaign group PETA have written to UEFA president Michel Platini to urge the governing body to stop ritual animal slaughters at clubs.
The group have called for a ban following news that Kazakh side Shakhter Karagandy sacrificed a sheep ahead of their 2-0 win over Celtic earlier this week.
PETA associate director Mimi Beckhechi said: "We are deeply disturbed that a sheep was stabbed to death in an attempt to bring good luck to the Kazakh team.
"We hope Mr Platini will agree that animal sacrifice has no place in modern society, and we hope the UEFA will act swiftly and decisively to ensure that the beautiful game is not further stained with the blood of animals."
It is believed that after killing the sheep, the animal was carried out onto the pitch on a cart.
