Paris - A look at major doping scandals involving the Tour de France since the Festina affair in 1998:
* 1998: Festina medical team member Willy Voet was arrested at the French border before the start of the Tour after customs officers seized banned substances, including the blood-boosting drug erythropoietin (EPO).
Festina were kicked out of the race and their riders later admitted to taking performance-enhancing drugs. Top rider Richard Virenque was banned for nine months, team director Bruno Roussel and Voet were fined and given suspended jail sentences.
* 2006: American Floyd Landis became the first Tour winner to fail a drugs test during the race after testing positive for the male sex hormone testosterone. Landis was stripped of the title and given a two-year ban.
Germany's 1997 Tour winner Jan Ullrich and Giro d'Italia champion Ivan Basso were among nine competitors withdrawn on the eve of the prologue after being implicated in a Spanish doping investigation, Operation Puerto.
Ullrich, who retired from competition in 2007, admitted to blood-doping under the guidance of the Spanish doctor at the centre of the Operation Puerto scandal.
Basso admitted his involvement in the scandal to the Italian Olympic Committee in May 2007 and was banned for two years.
* 2007: Pre-race favourite Alexander Vinokourov tested positive for blood doping after winning a time trial. The Kazakh's Astana team left the Tour and sacked Vinokourov, who denied any wrongdoing.
The Cofidis team pulled out of the race following Italian Cristian Moreni's positive test for testosterone. Moreni was suspended for two years.
Tour leader Michael Rasmussen was sacked by his Rabobank team during the race for lying about his whereabouts in training. He was banned for two years by the Monaco Cycling Federation for violating anti-doping rules.
German Patrik Sinkewitz was suspended after a test taken in June was positive for elevated levels of testosterone. Sinkewitz had already pulled out of the Tour injured following a crash with a spectator.
Spanish rider Iban Mayo, who finished the race in 16th place, was suspended by his team Saunier Duval after cycling's governing body confirmed traces of EPO in a sample taken during the race.
* 2008: Italian Riccardo Ricco was kicked out of the race after failing a test for the new generation of EPO called CERA (Continuous Erythropoiesis Receptor Activator). Saunier Duval then announced they were withdrawing their sponsorship of the team.
Austrian Bernhard Kohl, third overall and the race's top climber, as well as Italian Leonardo Piepoli and German Stefan Schumacher were also found guilty of using CERA following retroactive tests.
Kazakh Dmitriy Fofonov tested positive for the banned stimulant heptaminol and was fired by his Credit Agricole team. Spaniards Manuel Beltran and Moises Duenas Nevado tested positive for EPO. Barloworld ended sponsorship of their team after Nevado's test result.
* 2012: Luxembourg's Frank Schleck tested positive for the banned diuretic Xipamide during the second rest day and was withdrawn from the race by his RadioShack team. He was suspended for one year.
In June, the United States Anti-Doping Agency (Usada) recommended charging seven-times Tour winner Lance Armstrong, who won the race from 1999 to 2005, with using performance-enhancing drugs during his career.
After initially saying he would fight the charges, Armstrong changed his mind and in August Usada stripped him of his Tour titles and banned him for life.
Usada said in its report that Armstrong and his U.S. Postal team had run “the most sophisticated, professionalised and successful doping program that sport has ever seen”.
In January 2013, Armstrong admitted in a television interview he used banned substances in all of his Tour victories.
* 2014/2015 Defending champion Vincenzo Nibali's Astana team came under scrutiny from the International Cycling Union who wanted to strip them of their World Tour elite licence following an investigation into doping after several of their riders failed tests.
The independent licence commission, however, ruled in April that the Kazakh-funded outfit should keep their licence subject to strict monitoring of a number of special measures. – Reuters