Iban Mayo (pictured), Leonardo Piepoli, Alessandro Petacchi and their respective Saunier Duval and Milram teams have insisted they are not involved in a doping scandal after it was leaked that the three riders had given ?non negative? results in anti-doping tests carried out during the Giro d?Italia.

According to reports in Italy?s Gazzetta dello Sport newspaper and other sources, Mayo failed a testosterone test during the Giro after winning the 19th stage to Terme di Comano. He has a special certificate issued by the UCI that accepts he has a naturally high testosterone ratio. However the urine sample involved has been sent to a lab in Barcelona for further independent testing to see if the testosterone was produced by Mayo?s body or if it is synthetic and so possibly taken to boost his performance.

His Saunier Duval team have not officially been informed of the results because the testing and investigation is still on-going but moved quickly to explain that Mayo has a natural high testosterone level.

?Officially we haven?t been told anything,? directeur sportif but everybody knows Mayo has a special certificate,?Joxean Fernández Matxin told the Diario Vasco newspaper in Spain.

According to Gazzetta dello Sport, who have close links to the Rome anti-doping lab that carried out the initial tests, Petacchi and Piepoli both resulted ?non-negative? for salbutamol, a drug that is present in medicines used to treat asthma and allergies but that is also a banned steroid.

Both Petacchi and Piepoli have special TUE (theraputic use exemption) certificates that means they can use medicines containing salbutamol but this only allows levels of up to 1000ng/ml in anti-doping tests. According to Gazzetta dello Sport, both riders had levels higher than the limit. As a result their samples have also been sent to Barcelona for extra tests that can discover if they took the drug with an inhaler or with an illegal injection.

Petacchi rode his first race since the Giro d?Italia on Wednesday, finishing in the bunch at the Veenendaal-Veenendaal race in Holland after working for his team mate Vigano in the sprint. His Milram team denied their was any thing suspicious about his ?non-negative?.

?We haven?t been given any official information but one thing for sure is that Petacchi underwent six urine tests during the Giro d?Italia and has had a UCI medical certificate that has allowed him to take asthma medicines for years,? Milram team manager Gian Luigi Stanga told Gazzetta dello Sport.

?I?ve no reason to think that Alessandro has done anything differently compared to the past and we?re going to calmly wait for the result from Barcelona.?

Piepoli, who is riding the Dauphine Libere race in France, also played down the results of his ?non-negative? test.

?I take salbutamol to treat my allergies,? he said.

?Gianetti (Saunier Duval team manager) asked me how many inhalations I?d done but I take it whenever I need it, it depends on the time of year.?

Both the Saunier Duval and Milram teams were angry that the names of their riders had been leaked to the press, causing more bad headlines for cycling just a few weeks before the Tour de France. The UCI also refused to comment on the three cases until the results of the further tests and doping investigations were carried out.

If the UCI accept that the non-negatives were caused by medicinal use of salbutamol and or a natural high level of testosterone, Petacchi, Piepoli and Mayo will not face disciplinary action. However, if the cases are not cleared up, all three riders could join the growing list of riders not welcome in London for the start of the Tour de France.