The British supermodel, 42, has reportedly fallen out with the 24-year-old Canadian beauty on the set of their new modelling reality TV series, leaving the show's host Nigel Barker to act as a mediator, reported the New York Post.
"Nigel is the only one who gets along with everyone. He's been left as the host and the referee. You've got three models, all at different stages of their careers and different ages, and they are really not getting along. It's a competition show, and none of them are used to losing," a source said.
"Naomi doesn't have to have a reason not to like somebody. She just doesn't like certain people.
"There were some issues with Coco being on time and Naomi not being on time and Coco getting annoyed. Coco's a Jehovah's Witness, and she believes in being correct and polite and being on time. She doesn't drink. She's super straight-laced. So it's been a real mess between (Coco and Naomi)," the source added.
Former 'America's Next Top Model' judge Barker was reportedly overheard discussing the model's catfight at a charity benefit in New York hotspot Pink Elephant.
Campbell also hinted at the spat on Twitter when she wrote, "'I don't need a certain number of friends, just a number of friends I can be certain of."