Martin is particularly annoyed that the International Cycling Union (UCI) let Froome ride in the time trial at the Road World Championships on September 20 despite telling him that day about his adverse analytical finding at La Vuelta a Espana a fortnight earlier.

Froome came third in Bergen, winning a bronze medal that he said at the time "capped an amazing season". Martin finished a disappointing ninth.

In its letter to Froome and his national governing body, British Cycling, the UCI made it clear that he was not subject to a mandatory suspension.

One of the sport's most respected riders, Martin wrote: "I am totally angry. There is definitely a double standard being applied in the Christopher Froome case.

"Other athletes are suspended immediately after a positive test. He and his team are given time by the UCI to explain it all. I do not know of any similar case in the recent past.

"That is a scandal, and he should at least not have been allowed to appear in the World Championships.

"Not only the public, but also I immediately have the impression that there is wheeling and dealing going on behind the scenes, agreements are being made and ways are being sought as to how to get out of this case. Do he and his team enjoy a special status?

"These actions are major blow to the difficult anti-doping fight...we need a consequent and transparent approach by the UCI. What is going on here is inconsistent, not transparent, unprofessional and unfair."

In a test taken after the Vuelta's 18th stage on September 7, Froome provided a urine sample with a concentration of the asthma drug salbutamol of 2,000 nanograms per millilitre (ng/ml), double the World Anti-Doping Agency's limit of 1,000 ng/ml.

Team Sky said in a statement on Wednesday that the 32-year-old British star experienced "acute asthma symptoms" during the final week of the Vuelta and increased his dosage of salbutamol, within permissible limits, on doctor's advice.

Froome said on Twitter on today: "It's sad seeing the misconceptions that are out there about athletes & salbutamol use. My hope is that this doesn't prevent asthmatic athletes from using their inhalers in emergency situations for fear of being judged. It is not something to be ashamed of."

He then added in response to a reply to that post: "I didn't take more salbutamol than permitted, I've made that very clear. I'm also looking at the bigger picture. This enquiry will come and go, but the stigma will remain."

It is understood that Froome, who had struggled the day before but returned to form on stage 18, took three extra puffs on his inhaler after the finish but before his test.

[social=twitter]https://twitter.com/chrisfroome/status/941257918015528960/social]

He and his team are now trying to build a scientific argument to explain how this unusual, but legal, dose translated to an illegal concentration of the drug in his sample.

If Froome fails to provide a satisfactory answer, the UCI could proceed with an anti-doping rule violation which could strip him of his victory at the Vuelta - the first by a British rider and half of a Tour de France/Vuelta double only achieved twice before in cycling history - and result in him missing a large chunk of 2018.

Speaking to Sky Sports News HQ from a training camp in Majorca, the four-time Tour winner said: "This is damaging. It's come as a huge shock to me as well.

"At the same time I know within me that fundamentally I have followed the protocol, I have not overstepped any boundaries and I hope by the end of this process that will be clear to everyone and I'll be exonerated of any wrongdoing."

He explained he was tested every day he was in the leader's jersey at the Vuelta, which he wore from stage three to stage 21, and he knew he would be tested every day.

Giving an insight into how his case will proceed, Froome said Team Sky has given the UCI a "vast" amount of information about his dosages, what he ate and how often he peed, which could be key as dehydration plays a big role in how salbutamol is excreted and metabolised.

When asked how the adverse finding could have come about, Froome said: "My asthma was playing up a lot more and that's when the doctor advised me to increase the number of puffs, obviously staying well in the legal limit of the maximum allowed number of puffs you can take during the race.

"So we did increase it and that's why we're faced with this question of 'I did stay within the limits but obviously the test results show a different reading' so we're trying to evaluate what has happened."

Brian Cookson, who was president of the UCI at the time the adverse finding was discovered, said he had "no role or influence" in how Froome's case, or that of any other rider, had been handled.

"Under procedures introduced during my time as UCI president all anti-doping matters were dealt with by the totally independent CADF (Cycling Anti-Doping Foundation) and the Legal Anti Doping Service supervised by an external lawyer," he said in a statement.

"As UCI president I therefore had no role or influence in any individual case. I had then, and still have today, confidence in the integrity of all those involved, that they would always follow the correct procedures in every case, and that no rider was treated in any way differently from any other. I cannot comment further on this or any other ongoing case."

Cookson lost out in the UCI presidential election to Frenchman David Lappartient on September 21.