Cycling's global governing body the International Cycling Union (UCI) has announced that Russian rider Valery Kaikov had been suspended provisionally after failing an out-of-competition doping test.
The UCI said that it acted after a lab in the German city of Cologne, accredited by the World Anti-Doping Agency, found that an A-sample of Kaikov's urine contained GW1516 sulfone.
The substance was found in a test conducted on March 17 and is a so-called metabolic modulator, which helps boost the production of hormones which can enhance an athlete's performance.
"The provisional suspension of Mr. Valery Kaikov remains in force until a hearing panel convened by the Russian Cycling Federation determines whether he has committed an anti-doping rule violation under Article 21 of the UCI Anti-Doping Rules," the governing body said.
Kaikov was immediately sacked by his team, UCI ProContinental outfit Rusvelo.
"Immediately Kaikov's contract with the Russian team has been terminated and UCI Administration has been notified about this incident, the team said in a statement posted on its website.
"Moreover Rusvelo team declares that the main team´s ideology is zero tolerance to doping in cycling. We do support clean cycling and we will stick firmly to our policy."
Kaikov is the first athlete to officially return an adverse analytical finding for GW501516, and comes after the World Anti Doping Agency (WADA) issued a warning to athletes about the substance.
"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," said WADA in a March statement.
Clinical trials undertaken by pharmaceutical giant GlaxoSmithKline have indicated that the substance caused cancerous tumours in organs.
"GW501516 was a developmental drug that was withdrawn from research by the pharmaceutical company and terminated when serious toxicities were discovered in pre-clinical studies.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," said WADA.
The RusVelo rider has the right to request a test of his B sample.