Chris Froome has insisted that he did not overuse his inhaler beyond prescribed limits during a difficult BBC Sports Personality interview.
The four-time Tour de France winner admitted it "really is quite a horrible situation", responding to questions from Clare Balding last night.
Speaking from a training camp in Majorca, Spain, Froome explained: "I understand the concerns.
"I've been a bike rider now for 10 years and I know how some people might look at our sport and that's a responsibility that I take really seriously.
"I am an asthmatic and I have been since I was a child and I use a puffer to help me manage my asthma but I've never taken more puffs than I'm allowed.
"So this really is quite a horrible situation if I'm honest and we're working as hard as we can to try and get down to the bottom of this."
Froome, who won a fourth Tour last July, had double the permitted level of salbutamol in a urine test taking during his victory in La Vuelta, the Tour of Spain.
The result is not automatically classified as a positive test and the 32-year-old has not been suspended, but he must provide a satisfactory explanation for the test results or he faces a ban and the loss of his Vuelta title.
Froome has denied any wrongdoing and said he is providing all the necessary information to the UCI.
Speaking during the Sports Personality of the Year awards, he also said winning the Tour de France for a fifth year would be a "dream come true".
Meanwhile, David Walsh, the journalist who played a crucial role in uncovering Lance Armstrong's doping programme, has admitted he no longer trusts Froome as he used to.
Walsh has been a long-time defender of Froome's reputation in the face of years of speculation about the cyclist and Team Sky's commitment to their clean-riding mantra. But he said that in the wake of Froome testing for double the permitted limit of the asthma drug Salbutamol, "it leaves (Froome) with a question that will take some answering".
"There is a threshold level and Froome exceeded that by 100%," Walsh said. "He has to explain how that amount got into his body. If the authorities are not satisfied, he will be banned and stripped of his Vuelta title.
"The greater punishment will be to his reputation... he will be seriously damaged. Four Tour de France victories diminished in one asterisk."
Walsh said he spoke to Froome for an hour on Friday in a "fraught, difficult conversation".
When Walsh suggested he should have accepted responsibility when informed of the test result in September, Froome was "disgusted" by the idea.
Walsh added: "The hardest thing about our conversation was telling him that I no longer trusted him in the way that I once did."