Riders and managers who have been involved in past doping practices have been urged to come forward by Brian Cookson.
Canadian cyclist Ryder Hesjedal, winner of the 2012 Giro d'Italia, said on Wednesday that he doped "more than 10 years ago".
Peter Sagan of Cannondale left behind his rivals to triumph in the GP de Montreal in Canada.
Portugal’s Rui Costa continued a memorable week at the Tour de France by winning a rain-soaked mountainous stage 19 in Le Grand-Bornand.
Dan Martin won stage nine of the Tour de France as Chris Froome had to dig deep to retain his leader's yellow jersey.
Team Sky locked up the mountains last year to help Bradley Wiggins win his maiden Tour but this year's strategy will differ.
American Christian Vande Velde is out of the Tour de France after being involved in a crash early in the seventh stage.
Tour de France team Garmin-Sharp had a tough day in the office when two of their top riders crashed in the fifth stage.
The first stage of the Tour de France, claimed by Marcel Kittel, was overshadowed by a huge crash involving Mark Cavendish.
Rivals are lining up to target Team Sky's hopes of consecutive Tour de France victories this summer.
Tour de France
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