UKAD announced on Wednesday that they had insufficient evidence to bring any charges after investigating a so-called 'mystery package' delivered to the British rider at the 2011 Criterium du Dauphine.

It had been alleged by British newspaper the Daily Mail that the package contained triamcinolone, a banned substance which allows riders to lose weight while maintaining power. But UKAD said its investigation had been hindered by British Cycling's lack of medical records and they weren't able to establish whether the package contained triamcinolone or the legal substance fluimucil.

"Our investigation was hampered by a lack of accurate medical records being available at British Cycling," UKAD chief executive Nicole Sapstead said. "This is a serious concern."

But Wiggins, who is now retired after becoming the first Briton to win the Tour de
France and Britain's most decorated Olympian, said that there was "no evidence" against him and that he was disappointed by UKAD's actions.

The 37-year-old said the period of the investigation had been "a living hell for me and my family, full of innuendo and speculation. At times it has felt like nothing less than a malicious witch hunt."

Team Sky was established in 2009 by Dave Brailsford, the mastermind behind Britain's 14 cycling medals at the 2008 Beijing Olympics. Brailsford held dual roles with the British Cycling governing body and Team Sky, which has led to a string of questions concerning the line between the two, theoretically distinct, organizations.

Though they didn't refer to the alleged failure to keep detailed medical records, Team Sky said: "We have co-operated fully with UK Anti-Doping over the last year."

The British parliamentary inquiry, which investigated the incident, plans to issue a report by the end of the year. Damian Collins, who heads the sports committee, said he still believes there are "serious and worrying problems" within British cycling relating to anti-doping.

mp (AP, DPA)