Positive test may cost Bolt

Usain Bolt could lose one of his six Olympic gold medals after it was revealed Nesta Carter, his relay team-mate, was among the 31 athletes whose retested samples from the Beijing Olympics in 2008 proved positive for a banned stimulant.

Carter was the lead-off man in the Jamaica 4x100 metres relay squad that broke the world record in winning gold. Bolt, who anchored the team, won three gold medals in Beijing: 100 metres, 200 metres and in the relay, breaking world records in each race.

Sources said that traces of methylhexanamine were found in Carter’s ‘‘A’’ sample, part of a batch of 454 from the 2008 Games that the International Olympic Committee ordered to be retested.

Carter, 30, is the sixth-fastest man of all-time, having recorded a time of 9.78sec for the 100 metres in 2010. He was also part of Jamaica’s gold medal-winning sprint relay team at the London Olympics in 2012, as well as the World Championships in 2011, 2013 and 2015. He has not run this season because of a foot injury but is expected to attempt to qualify for the team for the Olympic Games in Rio de Janeiro at the Jamaican trials this month.

If Carter’s ‘‘B’’ test also turns out to be positive, he may face sanctions, which could include the relay squad being stripped of their medal. Methylhexanamine is a mild stimulant, which has been used as a dietary supplement and a nasal decongestant. It has been on the prohibited list of the World Anti-Doping Agency since 2004. It was reclassified in 2011 as a ‘‘specified substance’’, meaning that an athlete could have a ‘‘credible, non-doping explanation’’ for using it.

Historically, the sanction for the use of methylhexanamine has been a suspension of six months to a year and the loss of results from the period concerned.