Judo's governing body said that athletes were not obliged to take unscheduled drug tests when training in France in June and that those who refused, including Kosovo's gold medallist Majlinda Kelmendi, subsequently tested negative the next week.
The unannounced doping tests were organised during the training camp in Saint-Cyprien for French athletes, the International Judo Federation said in a statement on Tuesday.
The controller was surprised to also meet foreign athletes who had been training with the French and decided to test them by asking for their judo results in order to test the world's best athletes, the IJF said.
"Coaches from several countries were surprised by the procedures of this control and asked for advice from the IJF anti-doping specialist," the federation said.
"She cautiously expressed that in view of the reported facts, they had no obligation to do the test in those conditions."
Amid doubts over the testing, some athletes underwent tests while others, like Kelmendi and Martyna Trajdos of Germany, did not.
When informed about the case, IJF President Marius Vizer decided to test those who did not submit to the testing the following week, and the results were negative, the IJF said.
Agron Kuka, head of the Kosovo Judo Federation, told Reuters that Kelmendi had refused the drug test but said she was clean.
"Some person came in asking to do the test but didn't have any identification from WADA (the World Anti-Doping Agency) or anyone. It's just nonsense," he said, adding that they were in close contact with the IJF at the time over the situation.
"She became champion -- that's the story," he said.
The IJF told Reuters that Kelmendi had taken several drug tests this year, including in Rio on Sunday, the day she became the first athlete from Kosovo to win an Olympic medal.
Image: Kosovo's Majlinda Kelmendi Kosovo greets supporters after winning gold in the 52kg women's Judo event on Sunday
Photograph: Adrees Latif/Reuters
