Conor McGregor has hit out at Nate Diaz as he claimed USADA no longer name fighters who fail drug tests.
McGregor, who is preparing for his trilogy fight with Dustin Poirier in July, revealed he has been tested twice this week.
He went on to complain that he felt athletes who had been caught cheating were no longer named and shamed.
McGregor referenced an incident involving Diaz in 2019 when the welterweight was exonerated by USADA following an adverse finding in a drug test.
Diaz, who had maintained his innocence, was found to be the victim of a contaminated supplement and was cleared to fight Jorge Masvidal.
McGregor though, clearly remains irked by the situation, tweeting: "USADA tested me right before this [training]. Blood and urine. That’s twice this week. I don’t blame them, I’m a animal. What irks me tho is there is never an announcement of athletes caught anymore? This means [either] 1. They can keep it quiet [or] 2. Tainted supplement bullshit excuses are accepted.
"How come the public isn’t told about positive tests anymore?
"How after the Nate Diaz steroid debacle, where he produced his own nutrition companies tainted multivitamin [and] was instantly cleared prior to a mega money fight, are we now in the dark on test results?"
According to USADA's website, the last athlete to have been handed a suspension was Abu Azaitar who was banned for seventh months.
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Five fighters have been sanctioned this year according to the website which follows nine from 2020.
McGregor himself was tested eight times last year having fought just once; his 40-second KO of Donald Cerrone in January.
He has been tested on four occasions this year, including twice before his second-round defeat by Poirier three months ago.
McGregor will meet his lightweight rival for the third time this summer when the pair clash in Las Vegas in a fight which should determine the next 155lb title challenger.