UK Anti-Doping has confirmed it is examining multiple allegations of wrongdoing in cycling.
The Daily Mail reported on Thursday night that UKAD is investigating Team Sky and Sir Bradley Wiggins over the contents of a medical package delivered to the team in France in June 2011.
A UKAD spokesperson subsequently said on Friday that it was holding "one investigation on multiple allegations", although it refused to specify against whom.
A UKAD statement read: "We have confirmed that we are investigating allegations of wrongdoing in cycling. To protect the integrity of the investigation we will not comment further on this matter."
Team Sky insist there has been no wrongdoing and are liaising with UKAD.
A Team Sky statement read: "Team Sky was contacted by the Daily Mail regarding an allegation of wrongdoing.
"We take any issues such as this very seriously and immediately conducted an internal review to establish the facts. We are confident there has been no wrongdoing.
"We informed British Cycling of the allegation and asked them to contact UKAD, who we will continue to liaise with.
"Team Sky is committed to clean competition. Our position on anti-doping is well known and we 100 per cent stand by that."