The International Olympic Committee stripped three Kazakh weightlifters of gold medals won at the London 2012 Games for doping.
Zulfiya Chinshanlo, Maiya Maneza and Svetlana Podobedova were all caught in new testing of hundreds of samples from the London and 2008 Beijing Olympics.
A weightlifter from Belarus who won a bronze medal was also disqualified by the IOC. Russian weightlifter Besik Kudokov who won a silver in London also failed a doping test but the medal was not taken away because he died in 2013.
Chinshanlo, now 30, Maneza, 30, and Podobedova, 29, all tested positive for the steroid stanozol. Chinshanlo was also found to have taken oxandrolone, another steroid. Both substances promote muscle growth.
Chinshanlo won the 53kg category in London, Maneza won the 63kg gold and Podobedova the 75kg contest.
Marina Shkermankova of Belarus who took bronze in the women’s 69kg category was also among eight new doping cheats announced by the IOC.
98 competitors failed drug tests
The IOC has said that at least 98 competitors failed drug tests from Beijing and London after a new analysis was carried out on more than 1,240 samples using improved equipment.
About 10 gold medalists from London have now lost their titles or are at risk of losing them because of doping - four are athletes from Belarus.
Three Chinese weightlifting gold medal winners from Beijing have been stripped of their titles because of doping.
The doping scandal is a new blow to weightlifting. The International Weightlifting Federation has said it wants to ban Kazakhstan, Russia, Belarus and other nations for 12 months over doping.
But the scandal also heightens the stakes as the World Anti-Doping Agency (WADA) pursues its investigation into alleged state-sponsored doping in Russia.
More than 110 Russians were banned from taking part in the Rio Olympics after an inquiry by Canadian lawyer Richard McLaren gave details of the Russia scandal.
McLaren announced on Wednesday that the final part of his report would be released in early December.
IOC leader Thomas Bach has called for a major reform of WADA and the anti-doping system. WADA is to discuss proposals on who should carry out tests and sanctions at a meeting in Glasgow, Scotland on November 20.