The International Oympic Committee (IOC) has stripped cyclist Lance Armstrong of a bronze medal won during the 2000 Olympic Games in Sydney.
Thursday's letter, sent from the IOC to Armstrong, is the latest doping-related setback for the famed cyclist.
"Having had confirmation from UCI [Union Cycliste Internationale] that Armstrong has not appealed the decision to disqualify him from Sydney, we have written to him to ask for the return of the bronze medal,", Mark Adams, IOC spokesman, told the AP news agency.
"We have also written to USOC [United States Olympic Committee] to inform them of the decision.''
The decision was first reported on Thursday by The Associated Press news agency.
The IOC executive board discussed revoking the medal in December, but delayed a decision until the cycling body 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.
Sophisticated doping programme
The move was confirmed on the same day that Armstrong's admission of using performance-enhancing drugs, after years of denials, is to be broadcast in an interview with US talk show host Oprah Winfrey.
The timing of the IOC move, however, was not related to the TV interview.
Two months after winning his second Tour de France title in 2000, Armstrong took bronze in Sydney in the road time trial behind winner and US Postal Service teammate Vyacheslav Ekimov of Russia and Jan Ullrich of
The IOC opened a disciplinary case in November after a US Anti-Doping Agency report detailed widespread doping by Armstrong and his teammates.
The report called it the most sophisticated doping programme in sports.
The IOC will not reallocate Armstrong's bronze medal, just as the UCI decided not to declare any winners for the Tour titles once held by him.
Abraham Olano Manzano, of Spain, who finished fourth in Sydney, will not be upgraded and the bronze medal placing will be left vacant in Olympic records.
In August, the IOC stripped Tyler Hamilton, a former Armstrong teammate, of his time-trial gold medal from the 2004 Athens Olympics after he admitted to doping.
In that case, Ekimov was upgraded to gold.
The IOC is also investigating Levi Leipheimer, a former Armstrong teammate who won the time-trial bronze at the 2008 Beijing Games.
The US cyclist confessed to doping as part of his testimony against Armstrong in the USADA case.