The two new judges were filming an audition in Charlotte, North Carolina this week when they became embroiled in a huge argument over a contestant.
In video footage posted online, an angry Minaj can be seen shouting and swearing at the Hero hitmaker. Reports suggest Minaj continued the rant off camera and, in the heat of the argument, is said to have raged, "If I had a gun I would shoot her (Carey)."
Idol's executive producer Nigel Lythgoe quickly blasted the claims, branding them "absolute rubbish".
However, Carey remains alarmed by Minaj's alleged actions and confided in her pal, veteran U.S. broadcaster Barbara Walters, about her fears for her safety and that of her twin babies in a phone call on Thursday morning (04Oct12).
Recalling the conversation on her daytime talk show The View, Walters said, "What you heard was troublesome but that's not what really worried her (Carey).
"She said when Nicki walked off the set, multiple people heard Nicki say, 'If I had a gun, I would shoot that f**king b**ch...' (Carey) said she was very concerned, she was with the twins, she doesn't feel that anything would happen, but, 'Nicki is unpredictable'. Mariah says she can't take a chance and she has hired extra security."
Carey confronted Minaj about the death threats on Wednesday (03Oct12), but the rapper refused to apologise for her behaviour.
Walters continued, "Nicki has not apologised... There was a meeting yesterday morning. After the meeting, Nicki said to Mariah, 'I love you but we might fight again'. Mariah responded, 'No, we will not.' At this point Mariah said she doesn't feel comfortable emotionally, but she will continue with the show because she loves the show and she loves mentoring the contestants."
Carey's publicist has also issued a statement to Walters reaffirming the superstar's commitment to the 12th season of the hit talent show, declaring: "For the record, Mariah's doing well. She obviously still has serious concerns, but is hopeful that everyone will act in an appropriate, professional manner. She plans to move forward and she believes this season will be the best ever."