The news stems from an out-of-competition drug test collected by the United States Anti-Doping Agency (USADA)
UFC featherweight Chad Mendes has been flagged for a "potential Anti-Doping Policy violation" arising from an out-of-competition drug test collected by the United States Anti-Doping Agency (USADA).
Mendes, 31, has not fought since December 2015 when he suffered a first round KO at the hands of Frankie Edgar in The Ultimate Fighter 22 finale.
"The UFC organization was notified today that the U.S. Anti-Doping Agency (USADA) has informed Chad Mendes of a potential Anti-Doping Policy violation stemming from an out-of-competition sample collection," the UFC said in a statement.
"USADA, the independent administrator of the UFC Anti-Doping Policy, will handle the results management and appropriate adjudication of this case. It is important to note that, under the UFC Anti-Doping Policy, there is a full and fair review process that is afforded to all athletes before any sanctions are imposed. Additional information will be provided at the appropriate time as the process moves forward."
The organisation did not specify what banned substance was found in Mendes' sample.
Mendes has twice fought for the featherweight title, beaten both times by Jose Aldo once in 2012 and again in 2014. He was beaten by Conor McGregor in the second round of their interim featherweight title bout last July in Las Vegas.