Kazakhstan champions Shakhtar Karagandy have been warned that they could face disciplinary action if they slaughter any more sheep before European games, UEFA said on Wednesday.
"The UEFA Competition department has written to FC Shakhter Karagandy and informed them that animal slaughter was not acceptable in or around our competitions and that the club would face sanctions if it happens again," read a UEFA statement.
Animal rights group PETA last week called on UEFA to ban the ritual slaughter of animals after reports that Shakhter had killed a sheep before their Champions League playoff tie at home to Celtic which they won 2-0.
"We're very grateful for UEFA's swift and firm action condemning such cruel and archaic practices", said PETA's Mimi Bekhechi in a statement.
"UEFA has sent a clear message that there is absolutely nothing sporting about violence towards animals."
Shakhter were facing Celtic in Glasgow in their return match later on Wednesday for a place in the group stage of Europe's lucrative top tier club competition.