The International Olympic Committee has demanded the American return the medal after his results in all competitions were disqualified. The IOC's announcement comes only hours before Armstrong's expected admission of cheating on talk-show host Oprah Winfrey's programme.
The IOC acted after the International Cycling Union (UCI) stripped Armstrong of his seven Tour de France titles and disqualified all of his results as a result of him being found guilty of systematic doping. Armstrong had 21 days to appeal against the UCI's decision and, once it was confirmed he had not done so, the IOC took action.
An IOC spokesman said: "We have written to Armstrong asking for him to return the medal and informed the US Olympic Committee. It was a decision taken in principle at the executive board before Christmas. We were waiting for confirmation from the UCI that he hadn't appealed against his disqualification."
Winfrey already has revealed Armstrong came clean over his sordid past, which caused him to be stripped of his seven Tour de France titles and banned for life, when the interview was recorded on Monday in his home city of Austin, Texas. Armstrong was banned for life after the United States Anti-Doping Agency found he had been at the heart of "the most sophisticated, professionalised and successful doping programme that sport has ever seen".
Tour de France director Christian Prudhomme admitted he was surprised Armstrong had decided to come clean. He told French media: "No-one could have imagined he would publicly confess after years of denials, and denials that were firm and sometimes violent.But for us, Armstrong already is in the past. He doesn't have the seven titles any more."
French sports daily L'Equipe has looked ahead to Armstrong's appearance with a front-page headline stating The Night of the Liar, and writing: "After more than 10 years of lies, should we believe anything that Lance Armstrong will say on American television?"
WADA and the UCI, cycling's world governing body, have urged Armstrong to reveal all to the authorities if he is to have any hope of having his life ban lifted.
The motives for an admission – revealed by Winfrey – are unclear, but the Texan, who retired from cycling for a second time in 2010, was competing in triathlons until he was banned last year.
The Winfrey interview could be just the beginning for Armstrong, with a confession opening him up to a host of possible legal actions.
There are existing lawsuits involving SCA Promotions and The Sunday Times, while the United States Department of Justice could yet join a whistle-blower lawsuit filed against Armstrong by former team-mate Floyd Landis.
The False Claims Act lawsuit could mean that Armstrong is forced to repay a substantial sum to the US Government following its sponsorship of cycling through the US Postal Service.