The sanctions come amid a crackdown on Olympic athletes' use of banned performance-enhancing substances that has now spilled over to the Paralympics Games as well.
Controversies over doping overshadowed the build-up to this year's Rio Olympics and flared anew as U.S. and Australian competitors branded their Russian and Chinese rivals drug cheats.
In the latest move, the IOC disqualified Russian bronze-medallist weightlifter Nadezda Evstyukhina, silver-medalist weightlifter Marina Shainova, and Tatyana Firova, who finished second with teammates in the 4x400m track event.
The Russian Federation team was also disqualified from the women's 4x400m relay. All the sanctioned athletes were ordered to return any medals, pins or diplomas they had won in Beijing.
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Bronze-medal-winning weightlifter Tigran Martirosyan of Armenia and fellow weightlifters Alexandru Dudoglo of Moldova and Intigam Zairov of Azerbaijan were also disqualified, the IOC said in a statement.
It called on sports federations to modify the results of the Beijing Games that were affected and consider what other steps they found appropriate.
The IOC stores athletes' samples for a decade to test with newer methods or for new substances, and has in the past stripped medal winners of their prizes.
(Reporting by Michael Shields; Editing by Mark Heinrich)
