Shot putter Nadzeya Ostapchuk of Belarus became the first athlete to be stripped of a medal at the London Olympics after her gold was withdrawn on Monday for doping.
Valerie Adams of New Zealand was awarded the gold and Evgeniia Kolodko of Russia was bumped up to silver. Fourth-place finisher Gong Lijiao of China was moved up to bronze.
The International Olympic Committee said Ostapchuk tested positive for the steroid metenolone. She won the shot put exactly a week earlier. The IOC said she was tested the day before her competition and again following the event. Both samples were positive.
"The (Olympic committee) of Belarus is ordered to return to the IOC, as soon as possible, the medal, diploma and medallist pin awarded to the athlete in relation to the above-noted event,'' the IOC said in a statement.
The announcement came hours after the flame was extinguished at the closing ceremony with athletes and officials heading out of London. A day earlier, IOC President Jacques Rogge had proclaimed the fight against doping a success.
The Belarus team had already sent home hammer thrower Ivan Tsikhan because of suspicions over a sample provided after his silver-medal performance at the 2004 Athens Games.
Besides Ostapchuk, only one athlete tested positive for a banned substance after competing. US judo fighter Nick Delpopolo was cited for traces of marijuana in his urine sample. He blamed "inadvertent consumption'' of food baked with the substance.
The IOC disqualified him from seventh place in the 73-kilogram class.
Seven more were caught in doping controls conducted since the official testing period for the games began July 16. One of the seven competed in London before her test result was known.
"I think that is a sign that the system works,'' Rogge said Sunday.
"I am happy about the fact that we could catch athletes who cheated, both before the games and at the games.''
The IOC had said this would be its most extensive Olympic anti-doping program. It took almost 6,000 urine and blood samples, including no-notice tests ahead of athletes competing.
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Rogge cautioned that some samples are still being analysed and "we might hear something tomorrow or the day after. Hopefully not, but you never know.''
Syrian runner Ghfran Almouhamad tested positive for the stimulant methylhexaneamine two days before her 400-metre hurdles heat. She placed eighth and was eliminated before the IOC disqualified her.
Until this latest turn of events, the London Games were set to end with medal standings in all 302 events unaltered by doping scandals.
Three Beijing events were tainted during the games, and two more medals were changed months later when a new test for the blood-booster CERA was introduced. The signature men's 1,500-metre gold medal was stripped from Rashid Ramzi of Bahrain.
Rogge reminded that the IOC will store all samples from London and can reanalyse them, revise results and reallocate medals until the statute of limitations expires in August 2020.
"When there is no new tests, we wait until the last moment; if there is a breakthrough new test, we'll test immediately,'' he said.
Indeed, the next Olympic doping scandal could be from the 2004 Athens Games instead. Next week the IOC could announce up to five new disciplinary cases based on retested samples.