Frank Schleck has once again protested his innocence after failing a doping test during this year's Tour de France.
The Luxembourg RadioShack-Nissan rider tested positive for the diuretic Xipamide on July 14.
He requested his B sample also be tested, but confirmed on Friday that also came back positive.
Schleck maintains he has done nothing wrong, however, and is determined to prove that.
"Today I witnessed the analysis of the B-sample in the afld-lab in Chatenay-Malabry (France)," he said in a statement.
"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, whom I met, what materials I came in contact with, what nutritional supplements I took.
"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.
"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."
Schleck was 12th in this year's Tour, nine minutes and 45 seconds behind leader Bradley Wiggins, when news of his positive test broke and the cyclist immediately dropped out of the race.
Schleck is the older brother of 2010 winner Andy, who won the Tour de France after original victor Alberto Contador was stripped of his title for doping offences.
Cycling's governing body, the UCI, also confirmed Schleck's B sample had tested positive.
"The UCI communicates that the analysis of the sample B of Frank Schleck's urine carried out today has confirmed the result of the adverse analytical finding notified by the Anti-doping laboratory of Chatenay-Malabry following the analysis of the sample A," read a short statement.
"In accordance with the Anti-doping rules, the UCI will request the Luxembourg Federation to open a disciplinary procedure against the rider."
