(CNN) -- Frank Schleck is to leave the Tour de France after the International Cycling Union (ICU) revealed he had tested positive for a banned substance.
Schleck, from Luxembourg, finished third in the iconic race last year but his Radioshack team have said he will take no further part in the Tour after he tested positive for the diuretic Xipamide.
The 32-year-old is currently 12th place in this year's race, nine minutes and 45 seconds behind the leader, Team Sky's Bradley Wiggins.
A statement from the sport's governing body said a sample collected from Schleck on July 14 had failed their screening process.
"Earlier today the UCI advised the Luxembourger rider Frank Schleck of an adverse analytical finding (presence of the diuretic Xipamide...) in the urine sample collected from him at an in competition test," the UCI said.
"The UCI Anti-Doping Rules do not provide for a provisional suspension given the nature of the substance, which is a specified substance.
"However, the UCI is confident that his team will take the necessary steps to enable the Tour de France to continue in serenity and to ensure that their rider has the opportunity to properly prepare his defense in particular within the legal time line, which allows four days for him to have his B sample analyzed."
According to the World Anti Doping Agency, an offense involving a specified substance allows a tribunal more flexibility, and recognizes it is possible for such a substance to enter an athlete's body inadvertently.
"There is a greater likelihood that these substances could be susceptible to a credible non-doping explanation," their website explains.
Soon after the ICU's statement, Radioshack responded with one of their own stating Schleck would take no further part in this year's Tour.
It read: "After being informed by the UCI about the presence of Xipamide in the urine sample of Frank Schleck on July 14, the team has decided to immediately withdraw Frank Schleck from the Tour de France.
"Even though an abnormal A sample does not require these measures, Mr Schleck and the team believe this is the right thing to do, to ensure the Tour de France can go on in calm and that Frank Schleck can prepare his defense in accordance with the legal timing to do so.
"On the subject of Xipamide the team can declare the following: it is not a product that is present in any of the medicine that the team uses and the reason for the presence of Xipamide in the urine sample of Mr Schleck is unclear to the team.
"Therefore, the team is not able to explain the adverse findings at this point. However, the team is fully determined to collaborate with the anti-doping agencies in order to resolve the matter."
Schleck is the brother of Andy, who was belatedly awarded with the 2010 Tour de France title after Alberto Contador's original victory was wiped out for doping offences.