Armstrong was left upset by the way his comments were reported as it initially appeared he had said it remained impossible even now to win without doping, something he later clarified on Twitter.

For the record, there is a significant difference between WAS and IS. Past and present tense.

— Lance Armstrong (@lancearmstrong) June 28, 2013

For Tour general director Christian Prudhomme, the debate was an unwelcome distraction ahead of the opening stage of the race.

"I already said that we knew this was a horrific period for cycling," he said.

"Maybe we didn't know how horrific it was. It was at times scary for cycling.

"Maybe the only way for Armstrong to win was to take drugs."

Yesterday began with a bold headline in Le Monde which quoted Armstrong and read: "The Tour de France? Impossible to win without doping."

But Armstrong used Twitter to argue he had only referred to the years when he was competing for the famous yellow jersey, while saying he was "hopeful" current riders could win by legitimate means.

"99-05. I was clear with @StephaneMandard on this," Armstrong wrote, referring to the Le Monde journalist. "Today? I have no idea. I'm hopeful it's possible."

Armstrong's comments, and the initial portrayal of them as relating to the Tour today, had earlier brought a strong response from International Cycling Union (UCI) president Pat McQuaid.

In the interview, Armstrong suggested that doping had been so widespread in the sport a decade ago that only those involved could hope to contend. "My name was taken out of the palmares (list of achievements) but the Tour was held between 1999 and 2005 wasn't it?" he said.

"There must be a winner then. Who is he? Nobody came forward to claim my jerseys."

The 41-year-old also claimed McQuaid - currently facing a re-election challenge from British Cycling's Brian Cookson to remain as head of the sport's world governing body - must go if cycling is to clean up.

"(UCI president) Pat McQuaid can say and think what he wants. Things just cannot change as long as McQuaid stays in power," Armstrong said.

McQuaid then released a statement of his own which read: "It is very sad that Lance Armstrong has decided to make this statement on the eve of the Tour de France.

"However, I can tell him categorically that he is wrong. His comments do absolutely nothing to help cycling.

"The culture within cycling has changed since the Armstrong era and it is now possible to race and win clean...

"Armstrong's views and opinions are shaped by his own behaviour and time in the peloton. Cycling has now moved on."