UK Anti-Doping investigating 'allegations of wrongdoing'

"In order to protect the integrity of the investigation, we will not comment further," a spokeswoman said in a statement.

The Daily Mail newspaper had reported earlier that UKAD was investigating Team Sky and Bradley Wiggins about the alleged delivery in June 2011 of a medical package after the Dauphine Libere race and ahead of that year's Tour de France.

Team Sky said in a statement they had been contacted by the newspaper and immediately conducted an internal review to establish the facts.

"We are confident there has been no wrongdoing," it added. "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 percent stand by that."

Wiggins, the 2012 Tour de France winner, has been in the spotlight over his past use of Therapeutic Use Exemptions (TUEs), which allow athletes to take banned substances for verified medical needs and are signed off by sports federations.

The data was leaked last month by the Russian-based Fancy Bears cyber hacking site.

It showed Wiggins was given permission to have legal injections of the banned drug triamcinolone to treat breathing difficulties before the 2011 and 2012 Tour de France and 2013 Tour of Italy.

On each occasion the TUE was approved by British authorities and cycling's governing body, the UCI, and there is no suggestion Wiggins broke any rules.

Former Team Sky rider Jonathan Tiernan-Locke also alleged in a BBC interview that the painkiller Tramadol had been "freely offered" at the 2012 road world championships.

The BBC said British Cycling had put the allegation to the doctor concerned, who had denied it.