Cyclist Tony Martin questions why Chris Froome was not immediately suspended after testing positive in a doping control, while the four-time Tour de France champion reiterated his innocence.

Froome has to explain to the International Cycling Union (UCI) the high concentration of the asthma drug salbutamol in a urine sample he provided during the Vuelta a España he won in September. The amount of the substance was twice the permitted dose.

Although he admitted that the case is "negative" for a sport whose credibility has been affected by years of doping scandals, Froome stated that Team Sky has the necessary evidence to prove his innocence.

"I know I followed the protocols and did not break any rules," said Froome. "I hope that at the end of this process, it will be clear to everyone, and they will determine that I am innocent."

Froome defended his conduct in an interview with Sky, the sponsor of his team.

"I am tested every day of the race when I wear the leader's jersey, and I knew I would be tested," said Froome. "We also have all this team information about what I ate each day, how many times I urinated each day. We have a great deal of detailed information that we can provide."

Sky and the UCI confirmed the positive result on Wednesday.

Tony Martin, cyclist of the Katusha-Alpecin team, expressed suspicion about the way the UCI has handled the case.

"I am very upset," the German wrote on his Facebook account. "There is no doubt that there is a double standard with Christopher Froome in this case. Other athletes are immediately suspended after a positive result. The UCI gave him and his team time to explain everything. I do not remember a similar case in the recent past. That is a scandal, and they should not have allowed him to participate in the world championship at least."

"It's not just the public, I also had the immediate impression that there are negotiations behind the scenes, that agreements are being made, and ways are being sought to resolve this case. Does he and his team enjoy some special status?"

Cyclist Alejandro Valverde of the Movistar team indicated that the case is "a hard blow to cycling in general."

"Froome is the one who had the problem and it's normal that everyone talks about it," said the Spaniard, recalling that the British cyclist "tested twice the permitted amount."

The director of the Movistar team, Eusebio Unzué, regretted that "in cycling, we are always making great efforts to prevent these things from happening, and I don't know if, as a consequence of being more righteous than the Pope, mistakes continue to be made."

The UCI did not immediately respond to a request to explain its actions in the case, which Martin described as "a blow to the fight against doping."

Sky said Froome used twice the permitted dose of salbutamol after experiencing severe asthma symptoms during the last week of the Vuelta.

Salbutamol helps increase lung capacity and can be used to improve physical performance by increasing endurance. The World Anti-Doping Agency allows its use only through an inhaler, and in limited quantities.