United Kingdom, May 9 -- UFC CEO Dana White has revealed the "biggest d********" he has ever met.

The 56-year-old president and chief executive officer of the Ultimate Fighting Championship, a global mixed martial arts empire, called out rapper Sean 'Diddy' Combs as the "rudest celebrity".

When asked on a recent episode of The Katie Miller Podcast, who is the worst star he has met, Dana replied: "Good question, what a great question. Let me really think about this so I can really f****** stick it to whoever it was.

"Who did we run into that's.?" he asked someone off camera, who replied: "Diddy."

Dana went on: "Oh, Diddy, 100 per cent the biggest d******** ever."

White then revealed how Diddy once "scared" his niece, who had been a hu...