He served a nine-month ban after he failed a test for clenbuterol in February 2003.

In a statement released through his London solicitors Charles Russell LLP, Puerta said: “My position has always been that I did not deliberately or knowingly ingest any prohibited substance.

“The tribunal’s decision and its reasoning upholds and confirms this to be the case. The tribunal accept that the substance, etilefrine, entered my system entirely inadvertently and without my knowledge as a result of accidental contamination by an over-the-counter medicine which my wife was taking.

“Accordingly, it ruled that I bore ‘no significant fault or negligence’ for the substance having entered my system.

“The tribunal also accepted that the concentration of etilefrine in my sample, detected at a level many times lower than the laboratory is required to be able to detect it for the purposes of its accreditation, was so low as to be incapable of enhancing my performance.

“The tribunal also noted that the substance bore marked similarities with ephedrine which is treated much more leniently under the code and that the amount of the etilefrine in my sample was substantially less than the permitted level of ephedrine.

“Despite these facts, the tribunal found that it had no alternative but to apply strictly the rules which mandated an eight-year ban.

“The tribunal, with a ‘heavy heart’, was ‘very uncomfortable’ about imposing the ban, which it described as ‘particularly harsh’, and expected and indicated that it would ‘welcome’ an appeal to the Court of Arbitration for Sport.

“I find it extraordinary that it could ever be thought satisfactory that a person’s livelihood can be terminated in circumstances such as these.

“I will, of course, be considering an appeal with my lawyers but no decision will be taken until the New Year.”