Russia's anti-doping agency RUSADA has announced that Vladimir Dyatchin, the two-time world open water champion, has been provisionally suspended for failing a drug test.
RUSADA revealed that the samples that Dyatchin provided for testing at Russia's Open Water Swimming Championships on June 30 showed the presence of a prohibited substance.
The agency has not given any details of the prohibited substance.
They added: "The athlete has been suspended from participating in any capacity in a training camp or competition until the decision has been rendered on the case."
He is the 14th Russian swimmer to test positive in the last four years, an embarrassment to the country as it prepares to host the 2015 World Aquatics Championships in Kazan.
Other Russians currently suspended include breaststroke world record holder Yulia Efimova and European champion and world record holder Vitali Melnikov.
Efimova received a 16-month suspension earlier this year, and Melnikov is still under a temporary ban since early April.
The 31-year-old Dyatchin won gold in the 10 kilometres open water swimming at the World Championships in 2003 and 2007, as well as silver in 2001 and 2011 and bronze in 2003 and 2009.
In 2002 he also won European Championships gold in the same discipline.
In 2007 he was voted Swimming World's Open Water Swimmer of the Year.
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May 2014: London 2012 breaststroke medallist Efimova handed 16-month ban after positive test
January 2014: Swimming world record holder Efimova and a dozen other Russians latest caught up in doping scandal