Weightlifter Pat Mendes has been suspended for two years after testing positive for human growth hormone.

Mendes, the top-ranked American in the over-105-kilogram weight class, admitted he used HGH after it showed up in two samples tested at an accredited lab in Utah, the U.S. Anti-Doping Agency said in a news release Monday.

The 21-year-old from Las Vegas, who finished eighth at last year's Pan Am Games, became the first American in an Olympic sport to test positive for HGH and be disciplined for it. Last year, baseball player Mike Jacobs of the Colorado Rockies became the first North American pro athlete punished for taking HGH.

USADA CEO Travis Tygart said the positive test, combined with Mendes' acceptance of the ban, "further confirms there's no legitimate reason for this test to not be put in effect in the NFL and other pro sports."

The NFL and its players union have been trying to reach an agreement on how to implement HGH testing for more than six months. The players union has asked for more scientific data to prove the test is reliable.

Experts in the anti-doping movement said the test's reliability has been rigorously proven.

"The announcement today further demonstrates the scientific validity of the HGH test," NFL spokesman Greg Aiello said. "We look forward to resolving any remaining issues with the NFLPA and implementing the testing program agreed upon last summer" in the new collective bargaining agreement.

Union spokesman George Atallah did not immediately respond to a request from The Associated Press for comment. Union leaders and league executives met Monday in New York to discuss several issues, including HGH testing.