The seven-times Tour de France champion refused to mount a defence in the US Anti-Doping Agency’s case against him – which is seen in many circles to be as good as a confession of doping on Armstrong’s part.

However, Armstrong has insisted the USADA has a vendetta against him and, upon announcing that he would not mount a defence, said it was because he was “finished with this nonsense”.

“I have been dealing with claims that I cheated and had an unfair advantage in winning my seven Tours since 1999,” he said.

“There comes a point in every man’s life when he has to say, ‘Enough is enough’. For me, that time is now.”

Armstrong maintains his innocence and never failed a test during his career.

But his refusal to even present a defence – intended, he said, to save any further energies needed to clear his name – will surely cast doubt over that professed innocence.

Armstrong is the most successful rider in the history of the Tour de France, winning in consecutive years between 1999 and 2005.

His former team-mates Floyd Landis and Tyler Hamilton have publicly accused Armstrong of doping – but both men have also been punished for the same offence.

Armstrong called the charges against him an “unconstitutional witch hunt” and added: “Today I turn the page. I will no longer address this issue, regardless of the circumstances.”

He also wrote on his personal website: “The idea that athletes can be convicted today without positive A and B samples, under the same rules and procedures that apply to athletes with positive tests, perverts the system and creates a process where any begrudged ex-team-mate can open a USADA case out of spite or for personal gain or a cheating cyclist can cut a sweetheart deal for themselves.”

A spokeswoman for the USADA confirmed that Armstrong’s refusal to defend himself meant, “A loss of all results from August 1, 1998 and a lifetime ban from participating any sport sanctioned by a signatory to the WADA Code.”

USADA chief executive Travis T. Tygart said in a statement: “This is a heartbreaking example of how the win-at-all-costs culture of sport, if left unchecked, will overtake fair, safe and honest competition, but for clean athletes, it is a reassuring reminder that there is hope for future generations to compete on a level playing field without the use of performance-enhancing drugs.”

Armstrong responded: “If I thought for one moment that by participating in USADA’s process, I could confront these allegations in a fair setting and – once and for all – put these charges to rest, I would jump at the chance.

“But I refuse to participate in a process that is so one-sided and unfair. Regardless of what Travis Tygart says, there is zero physical evidence to support his outlandish and heinous claims.”

The cyclist also insisted that he defied the USADA to strip him of his titles.

“I know who won those seven Tours, my team-mates know who won those seven Tours, and everyone I competed against knows who won those seven Tours,” he said. 

Image: Getty