The 'I Got You' singer, who takes her Labyrinth tour to Glasgow tonight, has been a strict vegetarian since the age of 12 and is said to be banning people from even bringing in meat from outside.
"There are going to be murders. Leona has demanded that only veggie food be made available for everyone - and members of the crew are threatening to quit," a source told The Sun.
"She will not even allow food to be bought off-site then brought in. She is getting a reputation as a bit of a pain in the a**e. She is such a diva. It's getting out of control."
Lewis's support act Gabriella Cilmi recently expressed her concern to Digital Spy about eating on the tour, admitting: "All I know so far is that the food's going to be vegan, and I'm not sure how I'm going to cope with that."