Jamaican 4x100m relay sprinter Nesta Carter tested positive for a banned stimulant at the 2008 Olympics, a Jamaican newspaper reported Friday, placing one of Usain Bolt's six gold medals in jeopardy.

The Gleaner said a retest of Carter's 'A' sample from the Beijing Games had found traces of Methylhexaneamine.

The result of retests of Carter's 'B' sample was not yet known, the Gleaner said, citing "well-placed sources".

World Anti-Doping Agency spokesman Ben Nichols told AFP Methylhexaneamine had always been regarded as a prohibited substance under a "catch all category."

It was named specifically on WADA's prohibited list from 2010 onwards after the agency noticed a surge in cases involving the substance, which was attributed to it being included in supplements. 

It has appeared in nasal sprays and dietary supplements over the years.

Carter, 30, ran the first leg for Jamaica's 4x100m relay team in Beijing, which also included Michael Frater, Asafa Powell and superstar Bolt.

The team took gold in what was then a new world record of 37.10 seconds, ahead of Trinidad and Tobago and Japan.

Carter was also a member of Jamaica's gold medal-winning relay teams at the 2011, 2013 and 2015 World Championships as well as the 2012 Olympic Games.

If Carter is subjected to doping sanctions, it could mean Bolt stands to lose his relay gold.

In previous doping cases where individual members of a medal-winning relay squad have tested positive, the whole team is stripped of their medal.

The United States men's 4x100m team were stripped of their silver medals from the 2012 Olympics after Tyson Gay's doping case.

Britain's 4x100m team from the 2003 World Championships were also stripped of their silver medal following the Dwain Chambers case.

A notable exception came in the case of the USA women's 4x100 and 4x400m relay teams who were stripped of their medals after the doping scandal involving Marion Jones.

The relay teams successfully appealed against the decision at the Court of Arbitration for Sport, which found that rules at the time of the 2000 Olympics did not allow for the disqualification of an entire team on the basis of an individual member failing a doping test.

Source :AFP