Irish runner Cathal Lombard has been banned for two years after taking the performance-enhancing drug EPO.
The 28-year-old tested positive for the banned substance in an out of competition test last month.
The Irish Sport Anti-Doping Panel announced the verdict on Friday after Lombard's admission earlier this week that he had knowingly taken the drug.
Lombard, who had been set to compete in the 10,000 metres at the Olympic Games, refused to comment on the decision.
However earlier this week, the Cork-born solicitor apologised to his fellow athletes in a letter to the AAI.
"I have made a grave mistake and will pay a heavy price," he said.
The Irish Sports Council, which oversees the national
anti-doping system, said it had pursued Lombard after suspiciously
dramatic improvements in his performance in the past 18 months.
Lombard had slashed three minutes off his best time for the 10,000m.
The positive finding came at an out-of-competition test in Switzerland on 11 July.
In his letter, Lombard said that he hoped that his actions did not harm the sport in Ireland.
''I believe that athletics in Ireland is generally a clean sport,'' he said.
''What I have done is very negative for the
sport and I deeply regret that."
Lombard also stated that he wanted his Irish 10,000m record annulled and returned to Mark Carroll.
''Out of my respect for Mark Carroll and in the interest of the sport, I want the Irish 10,000m record set by me in April annulled and returned to Mark as soon as possible.''
Lombard again reiterated that his coach Joe Doonan had no inkling of his actions.
''Joe Doonan, my coach, had absolutely no involvement in, or knowledge, of my actions,'' he said.
''He is a wonderful man and a wonderful coach. I am
sorry for the hurt I have caused to him.
Lombard pledged to return to athletics after his ban ends.
"It would be my greatest wish now to join the fight against
doping," he said.