Nijel Amos, a 2012 Olympic silver medalist in the men's 800 meters, has been banned for three years for doping, the Athletics Integrity Unit said in a ruling published on Wednesday.

The runner from Botswana tested positive for the banned substance GW1516 last year in the run-up to the track world championships and received a reduction on the standard four-year ban because he admitted to the charges. The ban rules Amos out of next year's Paris Olympics.