British Cycling president Bob Howden insists he is prevented from confirming what was in a package delivered to Sir Bradley Wiggins five years ago due to the ongoing UK Anti-Doping investigation into the matter.
Wiggins announced his retirement on Wednesday but the contents of the package given to him at the end of a race in France in 2011 are the subject of a UKAD probe into alleged "wrongdoing".
Team Sky principal Sir Dave Brailsford told a Department of Culture, Media and Sport select committee last week that the package contained fluimucil, an over-the-counter decongestant available relatively cheaply in France.
But that does not explain why the team went to such expense to have it personally delivered to Wiggins by British Cycling coach Simon Cope. All parties deny wrongdoing.
Damian Collins MP, the chairman of the select committee, said in Thursday's edition of The Times that evidence provided by British Cycling failed to confirm Brailsford's explanation, adding that the "more we discover about the package, the more questions seem to be thrown up".'
But Howden told BBC Radio 4's Today programme that all the records needed to prove the drug was just a decongestant as claimed have been supplied.
"Obviously it's difficult to talk in detail about this because it's the subject of an ongoing UKAD investigation," Howden said.
"What I can say is that the information that was requested at the Commons select committee has been forwarded to the chair of that committee [Damian Collins].
"That included the information around what was in the package and who sent the package, and that has been sent through to the Commons select committee.
"The information has been sent through in terms of the details of the flights, the transportation details, that went with the package.
"What we're obviously not able to comment on are the actual exact medical requirements that were in place, because they are issues between doctor and athlete and it's a matter that UKAD are looking into."
Responding to Collins' concerns about the difficulty of getting precise records about what was in the package and why it was ordered, Howden said: "We forwarded the details around the transmittal of the package to the select committee.
"UKAD have the access to the records, they have the gateway, they have the keys to our medical room and all our records, so it would be for UKAD to confirm that, not British Cycling at this stage."
Collins added to the uncertainty surrounding the contents of the package in his interview with the Times.
"We now know from Simon Cope's expense claims that the request to take the package must have been made some time in advance, and that he travelled from southern England up to Manchester to collect it, and then went back [to southern England] to fly to France from London Gatwick," Collins said.
"If this medicine was needed urgently it would have been much quicker to buy it in France.
"We also know from last week's hearing that the medication was administered as soon as it was delivered. It also seems that British Cycling do not know categorically what was in the package.
"They say they understand it to be Fluimucil but do not explain why they understand that's what it was.
"We need to be sure that British Cycling do keep proper records of what goes in and out of their medical stores.''
Wiggins brought the curtain down on one of the most remarkable careers in British sporting history when he posted a statement on his Instagram page on Wednesday afternoon, accompanying a picture of his collected race jerseys, medals and trophies.
He bows out as the proud owner of eight Olympic medals -- a national record that includes five golds -- and became the first Briton to win the Tour de France in 2012.