LOS ANGELES (AP) -- UFC featherweight contender Chad Mendes has been suspended for two years after testing positive for a performance-enhancing substance.

The U.S. Anti-Doping Agency announced the sanction Wednesday. USADA administers the UFC's anti-doping policy.

USADA says Mendes tested positive for a growth hormone-releasing hexapeptide in an out-of-competition test conducted May 17.

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Mendes (17-4) is suspended until June 10, 2018, when he will be 33 years old.

Mendes has fought for the UFC 145-pound title three times, losing twice to Jose Aldo and once to Conor McGregor. The Northern California native has lost three of his last four fights overall, including a first-round knockout loss to Frankie Edgar in his most recent bout Dec. 11.

Mendes said on Twitter last month that he "didn't do my homework, and that was a big mistake."