Jonathan Tiernan-Locke has alleged he was offered a controversial and powerful painkiller while representing Great Britain at the 2012 Road Cycling World Championships.
Tramadol has been on the World Anti-Doping Agency's monitoring list for a number of years, with concerns over its side effects. Some members of the peloton believe its use has contributed to crashes.
Tiernan-Locke told the BBC: "There was a time I rode the World Championships and we were offered a painkiller called Tramadol.
"I wasn't in any pain so I didn't need to take it, and that was offered freely around. It just didn't sit well with me at the time.
"I thought, 'I'm not in any pain', why would I want a painkiller?'"
Sources within British Cycling say the team doctor at the 2012 Road Cycling World Championships denies the claim.
Tiernan-Locke was the leading British finisher at the race in Limburg, Holland, placing 19th.
Many riders and staff members had dual roles with British Cycling and Team Sky squads at the time.
Team Sky in 2014 insisted none of its riders used Tramadol after comments from former rider Michael Barry.
Former Team Sky and Endura rider Tiernan-Locke was stripped of the 2012 Tour of Britain title and banned for two years for an anomaly relating to his biological passport. He denies doping.
His Tour of Britain win helped him earn a contract with Team Sky, but he was sacked following his suspension.
Team Sky principal Sir Dave Brailsford, the former British Cycling performance director, recently defended the decision to get special permission for Sir Bradley Wiggins to receive injections of a banned drug before three major races, including his historic win in the 2012 Tour de France.
Wiggins used the powerful anti-inflammatory drug triamcinolone - a substance which has a history of abuse in cycling - on the eve of the 2011 and 2012 Tours and 2013 Giro d'Italia.
Wiggins applied, and was granted, three therapeutic use exemptions (TUEs) to take the drug to deal with a pollen allergy that aggravates his long-standing asthma condition.
The TUEs were approved by the UCI, cycling's world governing body, and there is no suggestion that he or the team have broken any rules.
