Jamaican Olympic sprint relay gold medalist Nesta Carter has tested positive for the banned stimulant Methylhexanamine, Reuters reports.
Carter's 'A' sample from the 2008 Olympics was retested along with 453 others, and was found to contain traces of the banned substance, an anonymous source has claimed.
If his 'B' sample also tests positive, Carter will face sanctions.
Carter won the gold in the 4×100 meters relay with Jamaican team mates Usain Bolt, Asafa Powell and Michael Frater in Beijing.
If his positive test is upheld, all four athletes will be stripped of their gold medals for the relay event, Bolt included.
So far, none of the athletes or the Jamaica Olympic Association have commented on the reports.
The retesting of the samples is part of an IOC programme aimed at using developments in testing techniques to identify banned substances that were undetectable in 2008 or 2012.
Samples from the 2012 Games in London are also being retested.
"We want to keep dopers away from the Olympic games in Rio de Janeiro. This is why we are acting swiftly now," IOC president Thomas Bach said last week.
"I have already appointed a disciplinary commission, which has the full power to take all decisions on behalf of the IOC."