Domino's Australia has apologized after serving animal meat to a vegan.
Patrick Hukins, from Sydney, said he felt 'sick to his stomach' after quickly realizing what had happened when he started eating the pie.
He wrote about the incident in several vegan Facebook groups - saying that the restaurant had provided poor customer service after he complained about the mistake.
Hukins told Daily Mail Australia that staff at the restaurant repeatedly reassured him that the meat on the pizza was plant-based ham, so he ate it.
"I had a horrible sinking feeling. I had eaten an animal. Not eating animals has become a core part of my belief system. I felt shame and pain for the animal...
"I felt betrayed. I have been vegan for four years, and having eaten an animal against my knowledge or consent has really thrown me off."
Domino's Australia messaged Hukins saying: "We ensure Domino’s team members can differentiate between the two products.
“Pizza is our passion and we want to ensure that everyone can share in the joy of pizza.
“Your feedback has been passed on to avoid the likeliness of this from happening again."
The latest incident is one of a number of examples of vegan fast-food customers being given animal-based ingredients in their order by a range of outlets.
Earlier this year, Papa John's in the UK caused a furor when multiple customers were given dairy cheese instead of plant-based, after outlets reportedly ran out.
The pizza giant responded to complaints saying: "Please rest assured that this is being looked into as a matter of urgency and being taken extremely seriously - we are looking to put things right asap."