Three-time Tour de France winner Chris Froome has described the rules allowing athletes to take drugs that would normally be banned under sport's anti-doping rules as "open to abuse" and in need of urgent reform.
In a post on his Twitter feed, Froome said he does not have a "win at all costs" approach to sport and has never pushed the boundaries of what is allowed.
And in an apparent reference to the controversy surrounding his former Team Sky team-mate Sir Bradley Wiggins, Froome said athletes need "to take responsibility for themselves, until more stringent protocols can be put in place".
Froome, who won his third Tour de France title in four years in July, added: "I take my position in sport very seriously and I know that I have to not only abide by the rules, but also go above and beyond that to set a good example both morally and ethically.
"It is clear that the TUE (therapeutic use exemption) system is open to abuse and I believe that this is something the UCI (cycling's governing body) and WADA (World Anti-Doping Agency) need to urgently address.
"At the same time, there are athletes who not only abide by the rules that are in place, but also those of fair play.
"I have never had a 'win at all costs' approach in this regard. I am not looking to push the boundaries of the rules.
"I believe that is something that athletes need to take responsibility for themselves, until more stringent protocols can be put in place."
My view pic.twitter.com/A7fGX6nDxU— Chris Froome (@chrisfroome) September 27, 2016