World champion weightlifter Aleksey Lovchev has been provisionally suspended after failing a drug test.
The Russian tested positive for a banned substance after last month's world championships in Houston, where he broke the clean-and-jerk and total world records on his way to the overall title in the 105 kilogram-plus category.
Russia's sports minister Vitaly Mutko claimed the banned substance, the growth hormone ipamorelin, was in a medicine he had been cleared to use.
The IWF said Lovchev's compatriots Aleksei Kosov, Olga Zubova and Olga Afanaseva also failed tests.
It is the latest doping drama to hit Russia after their athletics team was banned from all competitions in November for alleged systematic drug use.
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Three other medalists - South Korea's Kim Kwang-song and Kazakhstan's Almas Uteshov and Zhassulan Kyrdyrbayev - were among 24 adverse findings from the competition, the IWF reported.
