Former Tour de France podium finisher Frank Schleck has confirmed that a second 'B' sample has tested positive for a banned diuretic.
The result of the counter test was positive but for me nothing changes: I just know that I did nothing wrong.
Schleck, who finished third on the race last year, quit the Tour in disgrace Tuesday after being informed by the International Cycling Union (UCI) of a positive test for Xipamide.
Although Schleck has proclaimed his innocence, the UCI has asked his federation to take disciplinary action against the rider.
"In accordance with the Anti-doping rules, the UCI will request the Luxembourg Federation opens a disciplinary procedure against the rider," said a UCI statement.
Under UCI rules the 32-year-old could have continued in the race, his embattled RadioShack-Nissan team sent him home.
Diuretics are not considered performance-enhancing but can be used to help riders lose weight, and therefore perform better in the tough mountain stages of the race.
More ominously, they can also conceal the presence of a banned drug by helping to flush it from the body through increased urination. Xipamide, a diuretic, is normally used for the treatment of oedema and hypertension.
Schleck said in a statement that he will continue his fight to discover how the diuretic got into his system.
"The result of the counter test was positive but for me nothing changes. I just know that I did nothing wrong.
"I will therefore continue my search to find out how the substance could have entered my body.
"At the moment we are analysing minute by minute what exactly I have been doing, eating, drinking on the days before the control and on July 14 itself, who I met, what materials I came in contact with, what nutritional supplements I took."
Because Xipamide falls into a special category of substances under the World Anti Doping Code called 'Specified Substances', Schleck has a chance to prove his innocence.
The Code states that when an "athlete can establish that the use of such a specified substance was not intended to enhance sport performance, the period of ineligibility... shall be replaced with the following."
For a first violation athletes face anything from "a reprimand" or, at most, a "one year's ineligiblity".
A second violation would incur "two years ineligibility", in other words a two-year ban, while a third violation would incur a "lifetime ban".
"The medical world states that this product, when performing in extreme conditions such as in a cycling tour, is very dangerous; it can even cause death," Schleck's statement added.
"Therefore I really need to find the cause that clarifies how this product ended up in my system: since I didn't take anything, I assume it must have been given to me by someone, or it could have happened through an accidental contamination, or it could be caused by something that is not yet known to me since we are still undertaking a number of analyses.
"Since these extra analyses will take a few days, I will communicate again from the moment I have received the results of the extra tests."