The London Olympics chief Sebastian Coe says the 2012 Games will have the toughest anti-doping programme in history.
Coe says drug testers at London will be equipped with the most sophisticated anti-doping technology in Olympic history.
He says athletes who cheat will be caught, citing the triple-pronged enforcement strategy of the International Olympic Committee, London 2012 organisers and British police.
Coe says he can't guarantee an entirely clean games but organisers will do everything in their power to try to make that happen.