Belarussian Nadezhda Ostapchuk on Monday became the first medallist disqualified from the London Games for doping and was stripped of her women's Olympic shot put title.
The International Olympic Committee (IOC) confirmed that New Zealand's Valerie Adams has been awarded the gold medal after Ostapchuk provided two urine samples which were both found to contain the banned anabolic agent metenolone.
Ostapchuk said she would appeal against the IOC decision.
"Of course we will fight this decision but still it's not completely clear for what and against whom exactly we will protest," the 31-year-old told the Belarus service of Radio Liberty.
"We will make a decision after we get more information," Ostapchuk added.
Ostapchuk, the 2005 world champion, took surprise gold with a throw of 21.36m to end the almost two-year unbeaten run of 27-year-old Adams, who took silver with 20.70m.
Russia's Yevgeniya Kolodko has been upgraded to silver medal position and Lijiao Gong of China bronze.
An IOC statement had said earlier: "The athlete was first requested to provide a urine sample for a doping control on 5 August.
"She competed the next day in the women's shot put event, where she placed first, and was asked to provide a sample straight after her competition.
"Both samples indicated the presence of metenolone, which is classified as anabolic agent under the 2012 Prohibited List."
Adams, the 2008 Olympic and three-time world champion, said she was "speechless" after hearing the news.
"It is taking me some time to take this in," Adams told TVNZ from her base in Switzerland. It is huge and I am absolutely thrilled of course. It makes me extraordinarily proud as a New Zealander.
"It is also encouraging for those athletes, like myself, who are proud to compete cleanly, that the system works and doping cheats are caught."
Ostapchuk had been competing in her third Olympics in London. She finished fourth in Athens in 2004 and won bronze in Beijing four years ago.
While her positive test was the first by a medallist in London two other athletes were kicked out of the Games for failing drugs -- Syrian hurdler Ghfran Almouhamad and US judoka Nicholas Delpopolo.
Some podium hopefuls had been caught before leaving for London, such as defending 50km walking champion Alex Schwazer of Italy, Moroccan 1500m hope Mariem Alaoui Selsouli and Turkish weightlifter Fatih Baydar.
Belarussian hammer thrower Ivan Tikhon, a three-time world champion in 2003, 2005 and 2007, had also been excluded from competing before the Games as a result of drug tests dating back to the 2004 Olympics and 2005 world championships.
All doping tests from the London Olympic Games will be held for eight years and can be submitted for further testing in the future following scientific advances.
Two medallists from the Beijing Games -- 1,500m gold medallist Rachid Ramzi, of Bahrain, and Italy's road racing silver medallist Davide Rebellin were both stripped of their medals a year after the event.