Former Olympic 1500m champion Asbel Kiprop was tipped off by a doping control officer about a drugs test, but officials deny he was asked for money.
The Athletics Integrity Unit (AIU) confirmed the Kenyan, 28, tested positive for EPO after an out-of-competition test in November 2017.
The three-time world champion alleged his sample “turned positive” because he did not give the testers enough money.
That is rejected by the AIU, which said his sample was not tampered with.
However, the independent body which manages all doping-related matters for athletics said it is “extremely disappointing” Kiprop was provided with advance notice of the testing.
A tribunal will determine whether this has any effect on the case against the athlete.
Kiprop denied he has doped and said he paid the testers an unspecified amount of money via an electronic transfer and did not consider it untoward.
“At that time I did not see the money as an inducement or bribe,” he said.
“I gave it in good faith thinking they may have some need known to them.”
In a statement released via his lawyer on Thursday, Kiprop said:
“I did not at the time expect that the request for the money had anything to do with the sample,” said Kiprop, who says he is a police officer.
“In retrospect I now clearly see the money as having a relation with the sample collected on that date, and even the irregular advance notice I was given.
“I remain perplexed on how my innocent sample could turn positive on the only time when money was extorted from me.
“It is not beyond my suspicion that my sample turned positive because I might have remitted less money than I was expected to remit.”