A mysterious package delivered to Bradley Wiggins' doctor before the 2011 Tour de France contained a decongestant that is not subject to any anti-doping rules, according to Team Sky's general manager Dave Brailsford.
The content of the package is the subject of a UK Anti-Doping (UKAD) investigation, but appearing before a Parliamentary select committee Brailsford revealed for the first time that he has been told it was Fluimucil.
The drug, which was to be administered by a nebuliser, is used to clear mucus and is not subject to any controls by the World Anti-Doping Agency.
UKAD launched an investigation after the Daily Mail reported that a package had been delivered by a senior British Cycling coach to Team Sky on the final day of the 2011 Criterium du Dauphine at La Toussuire in the French Alps.
The package was handed to Team Sky's doctor Richard Freeman, who then undertook a medical consultation with Wiggins, who had won the race.
Until now, Brailsford and British Cycling officials have declined to discuss the substance, citing the UKAD investigation.
Brailsford has conceded that he made the situation worse by providing misleading information to the Daily Mail journalist who broke the story, initially telling him that the coach had not gone to La Toussuire.
But in a letter to the Culture, Media, and Sport Select Committee UKAD's chairman said he had no objection to the issue being discussed.
Shane Sutton, the former technical director of British Cycling, told the Parliamentary select committee that he authorised the delivery of the package to the Team Sky doctor at the conclusion of the Criterium du Dauphine.
Asked by committee chairman Damian Collins if Dr Freeman had told him what was in the package, Brailsford said: "Fluimucil. Dr Freeman told me it was Fluimucil for a nebuliser.
"It is a frequently used medicine, a drug we use on a regular basis, still do."
Brailsford said he believes the medicine was released in the UK by Team Sky physio Phil Burt.
He said he understood Wiggins' medical records had been shared with the UKAD investigation.
The existence of the package came to light following a leak of the cyclist's medical records, including 'Therapeutic Use Exemptions' (TUEs), by Russian hackers calling themselves Fancy Bears.
TUEs allow athletes to use otherwise banned substances, and in Wiggins' case allowed him to take triamcinolone, a corticosteroid, to treat allergies and asthma.
Many in the sport believe it is performance-enhancing and aids weight-loss.
Brailsford told MPs that he did not interfere with the medical team at Team Sky and trusted them to operate within the rules.
"You cannot work at Team Sky and not be aware of our culture," he said. "We are clean."
Earlier, Wiggins' former coach Shane Sutton told MPs he authorised the delivery of the package, from the then women's team coach Simon Cope, but did not know what was in it.
"I had no knowledge of the medical teams, (but) from my knowledge everything was above board and is above board," he said.
"Knowing the kid (Wiggins) for many, many years, as far I'm concerned he never worked outside any rules."
Sutton appeared angered at one point and suggested the MPs showed insufficient respect for Team Sky's achievements.
"I'm upset you've questioned the integrity of our team which, for me, led by Sir Dave Brailsford is not only the greatest sports team in British history, it's aligned with the All Blacks.
"I'm quite upset you feel that way."
Download the brand new OffTheBall App in the Play Store & App Store right now! We've got you covered!
Subscribe to OffTheBall's YouTube channel for more videos, like us on Facebook or follow us on Twitter for the latest sporting news and content.
