Luxembourg's Frank Schleck has been withdrawn from the 2012 Tour de France after testing positive for the banned substance Xipamide.
The announcement on Tuesday night came after it was discovered a urine test following Saturday's 13th stage on 14 July had revealed the presence of a banned diuretic.
Xipamide is used for the treatment of oedema and hypertension, and Schleck was informed of the result of his A sample by the Union Cycliste Internationale on Tuesday afternoon of the Tour's second rest day.
He now has four days to request a test on the B sample.
Schleck's team, RadioShack-Nissan, confirmed in a statement:
"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."
Schleck's removal is another instance of the doping sigma returning to taint the Tour.
On the first rest day of the Tour last week, Frenchman Rémy Di Gregorio was arrested for possession of illegal medical devices. He remains under investigation but was released on probation and has denied any wrongdoing.
In 2010, Spaniard Alberto Contador was stripped of the yellow jersey on doping grounds with Schleck's younger brother Andy anointed winner of the Tour. The Court of Arbitration for Sport only announced this decision was final in February this year.
Franck Schleck finished third in the 2011 event, and was in 12th place and nine minutes and 45 seconds behind Briton Bradley Wiggins in the lead.
The 32-year-old and his brother, 27, became the first siblings to stand on the final podium of the Tour in Paris last year.
