Sprinter Mark Lewis-Francis, who won Olympic relay gold last year, has been given a public warning by UK Athletics after testing positive for cannabis.
Lewis-Francis anchored the 4x100m relay team to gold in Athens
He has also been stripped of the silver medal he won in the 60m at this year's Spar European Indoor Championships.
Lewis-Francis, 22, avoided a two-year ban after claiming he ingested the drug passively rather than deliberately.
"My only explanation is that I may have been in the presence of people who were smoking cannabis," said Lewis-Francis.
"I have not knowingly taken this substance and have not attained any performance-enhancing benefits."
A UK Athletics statement said: "Mark Lewis-Francis provided a sample at the European Indoor Championships in Madrid, Spain on 5 March, 2005.
"The analysis of the sample identified the presence of cannabis. Cannabis is included as a specified substance on the 2004 Wada (World Anti-Doping Agency) Prohibited List."
The statement continued: "The athlete accepted the substance was present in his sample.
"Mark Lewis-Francis waived his right to a disciplinary hearing which he was entitled to under UK Athletics' and the IAAF's anti-doping rules."
UK Athletics said they were happy to issue a warning rather than a ban because it was the athlete's first anti-doping rule violation.
They were also satisfied that there was no intention to enhance performance.
"He has received exactly the penalty he should receive under the regulations," UK Athletics performance director Dave Collins told BBC Radio Five Live.
"The removal of the medal is quite a stark reminder that they (athletes) need to take every precaution to make sure they don't get in a position where they breach the doping rules."
Collins added: "I'm sure he's gutted. I'm sure he'll come back and work very hard for the summer."
Former sprinter John Regis, who won medals at world, Olympic, European and Commonwealth level, said Lewis-Francis had only got himself to blame.
"He's got to take more care of who he hangs around," said Regis. "I think it's naive and he should have been more careful. I know from my own career that you have to be careful.
"I never associated myself with anybody that could mean trouble, I knew people had the power to take away titles.
"You could say it was 'only' cannabis, it doesn't affect performance and if you took it a lot you'd be running backwards. But it's a banned drug, those are the rules and nobody can argue."
Lewis-Francis anchored the Great Britain 4x100m relay team to a shock victory in the Athens Games last August, edging out former Olympic 100m champion Maurice Greene by just a hundredth of a second.
At the European Indoor Championships in Madrid, Lewis-Francis had to settle for second place behind fellow Briton Jason Gardener.
Had Lewis-Francis been suspended, it would have futher weakened Britain's sprinting team following the loss of Dwain Chambers.
He was banned for two years in February 2004 for testing positive for the designer steroid THG.