The International Cycling Union said Tatyana Antoshina, a road racer included in Russia's national squad ahead of the Olympics in Rio, has been provisionally suspended after failing a drug test.
Antoshina, 33, tested positive for GHRP-2, a drug which stimulates the body's production of growth hormone, in a test taken May 31, the union said on July 4.
Antoshina races for the Astana team and has won multiple Russian national titles in road racing and time trial events, including a national time trial title last month.
Listed on the Russian national team, she was considered the likely reserve for two-time Olympic medalist Olga Zabelinskaya in road racing events at the August games in Rio de Janiero, Brazil.
Antoshina finished 12th in the time trial and 25th in the road race at the 2012 Olympics.