Three Russian Olympic medalists are among 11 weightlifters, mostly from ex-Soviet states, who tested positive for banned drugs in retests of samples from the 2012 London Games.
The International Weightlifting Federation announced the results on July 27 and provisionally suspended all 11 athletes until their cases are closed.
Four of the 11 are Russians, who all tested positive for dehydrochlormethyltestosterone, an anabolic steroid. Their heavy representation on the suspension list puts Russian weightlifters at risk of being barred altogether from the Rio Olympics next month.
The positive Russian tests came from Aleksandr Ivanov, silver medalist in the men's 94-kilogram division; Natalya Zabolotnaya, silver in the women's 75-kilogram division; Svetlana Tzarukaeva, silver in the women's 63-kilogram division; and Andrei Demanov, who placed fourth in the men's 94-kilogram division.
Ivanov was world champion in 2010 and 2013, while Tzarukaeva won the world title in 2011.
Medal winners from Armenia, Belarus, and Moldova also failed the retests: Hripsime Khurshudyan of Armenia (bronze, over-75-kilogram division), Iryna Kulesha of Belarus (bronze, 75-kilogram division,) and Cristina Iovu of Moldova (bronze, 53-kilogram division).
Also testing positive were Turkey's Sibel Simsek, Almas Uteshov of Kazakhstan, Georgia's Rauli Tsirekidze and Intigam Zairov of Azerbaijan.
Bulgarian weightlifters have been banned from the upcoming Rio de Janeiro Games because of the large number of positive doping tests, and now Russian weightlifters are also at risk of being banned.
The federation on July 25 said it had requested "further clarification" from the International Olympic Committee and the World Anti-Doping Agency before making a decision on which Russian athletes can be cleared to compete in Rio.
The Olympics committee decided against a blanket ban on Russian athletes at the Rio Games, despite evidence of widespread doping and cover-ups in Russian sports, and instead left it to individual sporting federations to decide who should be allowed to participate.
Olympic doping samples are stored for 10 years, allowing them to be reopened and reanalyzed when improved testing methods become available.
So far, 31 of the 98 doping positives discovered in the retests of samples from the 2008 Beijing Games and the 2012 London Olympics were weightlifters.
With reporting by AP and Reuters