Britain's Bradley Wiggins says this year's Tour de France has lost all credibility following the spate of doping controversies to hit the race.
Wiggins considered his future in the sport
Wiggins was forced to pull out of the race after a Cofidis team-mate, Cristian Moreni, was found to have tested positive for testosterone.
"No-one has faith in who is wearing the yellow jersey," said the 27-year-old.
"This year's Tour has lost all credibility. It's null and void as far as I am concerned this year."
Wiggins won Olympic gold in the individual pursuit at Athens 2004 and also claimed a silver in the team pursuit and bronze in the madison.
Speaking from a news conference in Manchester, he added: "It's been a hectic 48 hours.
"From finishing a seven-and-a-quarter-hour Pyrenean stage on Wednesday to being told straight away at the finish that we had to go to the police station on a bus.
"Then being dragged out of France after being questioned and flying home on Thursday.
"I'm quite pleased I'm here and out of it. I have no regret that I am not there. It's not a nice place to be.
Unfortunately there is the suspicion out there that you can't win it unless you are taking something
"Up to the point I had left it had been a fantastic race for me on a personal level."
Michael Rasmussen was sacked while leading the race for lying while Alexandre Vinokourov, Moreni and Patrik Sinkewitz have all failed drugs tests.
Alberto Contador is currently leading the race, which will finish on Sunday, but former Tour winner Greg LeMond believes the yellow jersey should not be awarded to anyone this year.
And Wiggins said: "As we stand, Contador is going to be a worthy winner as he hasn't failed any tests.
"But unfortunately there is the suspicion out there that you can't win it unless you are taking something.
"That's unfortunate if he is clean but you can't blame people for that doubt."
Wiggins was awarded an OBE for services to sport in the New Year's Honours List published 31 December, 2004.
It's not the end of the Tour or cycling
He continued: "I certainly won't go back (to the Tour) next year but that decision had already been made as the Olympic Games next year are my priority.
"The first 24 hours after it happened my initial reaction was that I was going to get out of the sport just through sheer anger.
"But once I had got home and seen the family and settled down a bit I thought I am willing to see this thing through.
"There are enough of us out there to make a big difference."
Wiggins believes the drug culture is more of a problem in the older generation in the sport and says the Tour organisers need to be more ruthless about which teams they allow into the event.
He believes teams or riders with a doubt over their credibility should not be invited to compete in a race he described as "essential for the sport".
He wants life bans for the culprits but insisted: "I'm angered by it. It's made me more determined to prove there can be clean winners even stronger.
"It's not the end of the Tour or cycling."