Two officials say the International Olympic Commitee [IOC] sent a letter to Armstrong on Wednesday night asking him to return the medal.
The move came after the IOC was notified by cycling's governing body that Armstrong had not appealed the decision to disqualify him.
The officials spoke to the Associated Press on condition of anonymity because the decision hasn't been announced.
The IOC executive board discussed revoking the medal last month, but delayed a decision until cycling body Union Cycliste Internationale formally notified Armstrong he had been stripped of his seven Tour de France titles and all results since 1998. He then had 21 days to appeal.
Now that the deadline has expired, the IOC has decided to take the medal away.
No invite for Amstrong
Armstrong's tarnished name is also unlikely to be on the massive list of invitees as Tour de France organisers prepare their celebrations for the 100th race this year.
As part of the festivities, all riders who managed to finish a Tour de France have been invited for the final day, with the total number of invitations numbering about 4 000. About 500 former riders are expected to be at the Champs-Élysées finish line.
Asked if Armstrong would receive one, Tour race director Christian Prudhomme looked stern-faced when he said on Thursday: "That seems to me to be out of place now."
Armstrong was stripped of his seven Tour titles and banned from cycling for life following a US Anti-Doping Agency report that portrayed him as a serial drug cheat.
After years of denials, he confessed to doping during an interview with Oprah Winfrey taped on Monday and to be aired later on Thursday.
"No one could have imagined that he would publicly confess after years of denials, and denials that were firm and sometimes violent," Prudhomme said after a presentation for the 2014 Tour, which starts from the English city of Leeds.
"No one could have imagined that, even a few weeks ago. I can't say more now because I don't know exactly what he will say, but it's obviously something striking."
Armstrong was always the main talking point of the race when he won his seven straight titles from 1999-2005, and when he unexpectedly came out of retirement to race in the 2009 and 2010 Tours.
"For us, Armstrong is already the past, he doesn't have the seven titles anymore," Prudhomme said. "What you have to understand is the mechanism (behind the doping)."
Prudhomme was expected to offer further comment on Armstrong on Friday after the airing of Armstrong's interview with Winfrey. Sports daily L'Equipe wrote "The Night of the Liar" in a teaser on its front page looking ahead to the show.
"After more than 10 years of lies, should we believe everything that Lance Armstrong will say [on Thursday] night on American television?" L'Equipe wrote. – Sapa-AP