MONACO (AP) — Nijel Amos, an Olympic silver medalist in the men's 800 meters, has been suspended ahead of the world championships after testing positive for a rare banned substance.

The Athletics Integrity Unit said Tuesday that the 28-year-old Amos gave a sample on June 4 which was found to contain GW1516, an experimental drug which can modify the body's metabolism but has been considered too dangerous for human use.

Amos had been set to race the 800 heats of the world championships in Eugene, Oregon, on July 20. He won silver at the 2012 Olympics, becoming the first-ever medalist for Botswana.

“The athlete was notified of the adverse analytical finding and his mandatory provisional suspension this afternoon in Eugene,” the AIU said.

GW1516 was developed to help build endurance and burn fat but was found to cause cancer during tests on rodents. Anti-doping organizations have warned athletes not to use it on safety grounds.

The drug has previously been found in samples given by professional cyclists and by Olympic race-walker Elena Lashmanova. The Russian served a two-year ban and was later stripped of the 20-kilometer gold medal she won at the 2012 Olympics for another doping offense.


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