MOSCOW (Reuters) - Russia's European track champion Valery Kaikov has become the first rider to test positive for a drug the World Anti-Doping Agency (WADA) has warned has serious health risks, his Rusvelo team said on Thursday.
"Kaikov had his contract terminated after testing positive for a prohibited substance," the team said in a statement.
"Rusvelo has a zero tolerance for doping and had already informed the International Cycling Union (UCI) about Kaikov's dismissal," added Katusha's reserve team who compete on the second-tier Continental Tour.
The UCI said that the 24-year-old rider, who won gold at last year's European track cycling championships in the team pursuit, returned a sample that showed traces of GW1516 - also known as GW501516.
GW1516 is said to enhance endurance.
"It has come to WADA's attention that the black market substance GW501516 is being sold to and used by some athletes," the WADA said last month.
"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"GW501516 was a developmental drug that was withdrawn from research by the pharmaceutical company and terminated when serious toxicities were discovered in pre-clinical studies.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," WADA added.
Kakov is the second Russian rider in five days to fail a drugs test.
Alexander Serebryakov, 25, who rides for Spanish outfit Euskaltel-Euskadi, was provisionally suspended by the UCI on Sunday after testing positive for the bloodbooster EPO.
Russian officials have been told to get tough on doping after the UCI rejected Katusha's application to compete in the top flight because of the team's doping record over the past four years.
Katusha, who finished second in the World Tour standings last year and have world number one Joaquim Rodriguez in their ranks, were reinstated in February after appealing to the Court of Arbitration for Sport.
(Reporting by Gennady Fyodorov and Julien Pretot, editing by Justin Palmer)