Russia and China are among nine countries to be given a one-year ban from international weightlifting after drugs tests came back positive. Armenia, Azerbaijan, Belarus, Moldova, Kazakhstan, Turkey and Ukraine have also been suspended.
The countries returned at least three positive results each after tests from the 2008 and 2012 Olympic Games were analysed again. They will miss the World Championships, which start in California in November.
The International Olympic Committee is retesting hundreds of samples, using new techniques to uncover cheating that went undetected at the time.
Earlier this year three Chinese weightlifters tested positive and faced having to return medals won at their home Games in Beijing in 2008.
Announcing the suspensions, IWF president Tamas Ajan said: “We have made it clear that the incidence of doping in some areas is totally unacceptable and that our members have a responsibility to ensure clean sport in their countries.”