BUDAPEST, Hungary (AP) — One of the United States' top weightlifters has tested positive for a banned substance in a sample he gave while competing for Armenia at the 2012 Olympics.

The International Weightlifting Federation says Norik Vardanian tested positive for the steroid dehydrochlormethyltestosterone in a retest of his sample from the London Olympics.

Vardanian was born in Armenia and represented that country when he finished 11th in the 94-kilogram class at the 2012 Games. He later switched to the U.S., winning silver at last year's Pan American Games.

Vardanian was previously banned for six months in 2009 after testing positive for cannabis.

A total of 43 weightlifters have now failed retests from the 2008 and 2012 Olympics, prompting concern among senior IWF officials over the sport's Olympic future.

Six more competitors from Vardanian's event at the 2012 Olympics are already facing disqualification after retests found steroids. That means Saeid Mohammadpur of Iran, who originally finished fifth, could be elevated to the gold medal, while bronze could end up with a competitor who was ninth.

Vardanian did not immediately respond to an e-mail request for comment.