UFC welterweight fighter Nate Diaz says he will not be fighting at UFC 244 after he says he's been told he tested positive with "elevated" levels" of an unknown substance.

Diaz took to Twitter to make the announcement on Thursday. He was to take part in the main event against Jorge Masvidal.

"Im not gonna make it out to NYC for fight week next week because they say I tested with elevated levels that they say might be from some tainted supplements," Diaz said. "I call false on that cause I only take Whole Food or natural food supplements. I don't even eat meat."

According to ESPN's Ariel Helwani, Diaz has not been provisionally suspended as of yet.