NICKI MINAJ

CUSSES OUT MARIAH

CAUGHT ON TAPE

Nicki Minaj derailed the "American Idol" auditions in Charlotte, North Carolina today, after swearing at Mariah Carey and threatening, "I'm gonna knock you out" ... sources tell TMZ.

In the footage, obtained by TMZ, Nicki is clearly furious ... shouting, "I told them, I'm not f*ckin' putting up with her f*ckin' highness over there."

Sources say Nicki later threatened to "knock out" Mariah ... but that part wasn't captured on tape.

It all went down while the two were sitting at the judge's table ... with Keith Urban sitting in between them and Randy Jackson sitting on the far end, next to Mariah.

We're told the whole thing exploded over a disagreement about a contestant's performance.

According to our friends at MouthToEars.com, producers ended the auditions for the day so the two judges could cool down.

Big wigs on the show seem uncharacteristically upset by the blow up -- it appears this was no joke and it seems producers are worried about Mariah and Nicki co-existing for the long haul.