Russian state TV says 14 of the country's athletes from the 2008 Olympics failed retests of their doping samples, including 2012 Olympic high jump champion Anna Chicherova.
Match TV says 11 of the 14 athletes are from track and field, including 4x100-meter relay gold medalist Yulia Chermoshanskaya. The others are two weightlifters and a rower.
If Chermoshanskaya is disqualified, the relay gold medal would pass to Belgium.
Another three silver and five bronze medals could be reallocated if all 14 athletes are stripped of their results.
Chicherova, who won bronze in Beijing in 2008 and gold at the London Games, was quoted by Match TV as saying she was "in the same shock as everyone else" when she received official notification of her positive test.