The World Anti-Doping Agency (WADA) had warned last month about the dangers of taking GW501516, which helps athletes burn fat, claiming it had some potential serious side-affects.

The International Cyciling Union (UCI) have confirmed that 24-year-old Kaykov, winner of a European Track Championship silver medal in the madison last year, has tested positive for the substance and he has been provisionally suspended.

His Russian team, RusVelo, which competes in the second-tier Pro Continental division, have also sacked him.

"The decision to provisionally suspend this rider was made in response to a report from the WADA accredited laboratory in Köln (Cologne) indicating an Adverse Analytical Finding of metabolite GW1516 sulfone – Metabolic Modulator in a urine sample collected from him in an out of competition test on 17th March 2013," said the UCI in a statement.

News of Kaykov's positive follows a memo sent around by WADA which said "the side effect of this chemical compound is so serious that WADA is taking the rare step of warning 'cheats' to ensure that there is complete awareness of the possible health risks to athletes who succumb to the temptation of using GW501516 for performance enhancement.

"GW501516 was a developmental drug that was withdrawn from research by the pharmaceutical company and terminated when serious toxicities were discovered in pre-clinical studies.

"Clinical approval has not, and will not be given for this substance."

Manufacturers GlaxoSmithKline had abandoned making the drug seven years ago after clinical trials involving lab rats showed that it caused tumours in a number of organs, including the liver, bladder, stomach, skin, thyroid, tongue, testes, ovaries and womb.

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