PARIS - The International Cycling Union (UCI) is under pressure to reveal how shamed US rider Lance Armstrong was able to escape detection for doping for so long.
According to a number of his former team-mates, the seven-time Tour de France winner bragged about having managed to suppress a positive test for the blood booster erythropotein (EPO) on the 2001 Tour of Switzerland.
The head of the Lausanne laboratory involved confirmed to US investigators that the sample in question was disputed, although given the science at the time, it was not considered strong enough evidence to put before a court.
Simply put, the "positive" test was an assumption. Tests for EPO had only been approved two months earlier.
"It wasn't possible for my predecessor (Hein Verbruggen) to hide the result," the current president of the UCI, Pat McQuaid, said in 2010, later saying: "There was no positive test."
But the formal position of the UCI and its refusal to allow the US Anti-Doping Agency (USADA) to re-examine the test without Armstrong's consent has prompted opponents to claim it is compromised.
More troubling still for the UCI is that it accepted two donations from Armstrong between 2002 and 2005 for a total of $125,000 (78,000 pounds, 96,000 euros), which were used to buy anti-doping technology, including a blood analysis machine.
"You have to consider the context at the time. In 2002, there were no claims of doping against Armstrong," McQuaid said in 2010, although he acknowledged that the organisation would be careful in future about any similar donations in future.
The former head of the World Anti-Doping Agency (WADA), Dick Pound has meanwhile accused the UCI of turning a blind eye to Armstrong's activities.
Others, such as the wife of the former Tour winner Greg LeMond, go further by raising the possibility of corruption, claiming that sportswear manufacturer Nike donated $500,000 to suppress a positive test on the 1999 Tour.
Kathy LeMond based her claim on a private conversation with Armstrong's former mechanic, Julien De Vriese.
But in testimony to Armstrong's lawyers, the Belgian denied saying what was reported in detail in the 2006 book "L.A. Official" by Pierre Ballester and David Walsh.
Nike, which is still a sponsor of Armstrong, also categorically rejected what it said were "unacceptable allegations".
On dope tests, the UCI has often said that it was not the only body aware of positive results while no concrete proof has emerged to back up claims that Armstrong and his sporting director Johan Bruyneel were tipped off in advance.
If it had, the implications would undoubtedly be serious but the UCI has stated that other bodies also conducted tests on Armstrong, including the USADA, and every time the results came back negative.
A French lawyer, Thibault de Montbrial, who represented the former sporting director of the Festina team after a doping scandal after the 1998 Tour, has suggested the former head of the UCI and Armstrong had close links for a reason.
Verbruggen's alleged protection of Armstrong stemmed from a need to see the Texan and cancer survivor as the new face of cycling after a damaging series of drug cases, the lawyer added.
It seems likely, for example, that the UCI accepted a probably post-dated certificate to justify Armstrong's use of a cortisteroid on his first Tour victory in 1999.
At the time, use of the drug, which reduces swelling and can be used to treat saddle sores, was not uncommon. Laurent Brochard, from the Festina team, argued that he used it for therapeutic reasons in his world championship winning year in 1997.
But the suggestion is that was not the only time the UCI did not make sure that Armstrong played by the rules.
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