Former Olympic 1,500m Champion Asbel Kiprop has been banned from the sport for four years for doping.
The 29-year-old Kenyan runner tested positive for erythropoietin (EPO) in an out-of-competition test in November 2017.
He however rejected the result of the tests, alleging that his sample may have been tampered with.
An anti-doping panel said “the case against the athlete is convincingly made out”.
The Athletics Integrity Unit (AIU), an independent body which manages all doping-related matters for athletics, also ruled his results and any winnings from November 2017 to February 2018 should go.
“The panel is aware that its order will interrupt and may even terminate the athlete’s sporting career and cast a shadow over his impressive competitive record,” said an AIU statement.
Kiprop’s ban is dated from 3 February 2018, and can be appealed should Kiprop deem it fit to do so.