(CNN) -- Three-time Tour de France winner Greg LeMond has told International Cycling Union (UCI) president Pat McQuaid to resign, accusing the Irishman of "abusing his power."
The UCI has come under fire amid the doping scandal that implicated Lance Armstrong in "the most sophisticated, professionalized and successful doping program that sport has ever seen."
Armstrong was stripped of his seven Tour titles and dropped by high-profile sponsors Nike and Oakley in the wake of the United States Anti-Doping Agency (USADA) report, and has yet to comment on it.
LeMond called on McQuaid and his predecessor -- honorary UCI president Hein Verbruggen -- to quit, insisting that progress in the sport can only be made if they step aside.
In an open letter on his Facebook page, LeMond -- who won the Tour in 1986, 1989 and 1990 -- reiterated his support for former Sunday Times journalist Paul Kimmage, who is being sued for defamation by the pair.
"I want to tell the world of cycling to please join me in telling Pat McQuaid to resign," he wrote. "I have never seen such an abuse of power in cycling's history -- resign Pat if you love cycling. Resign even if you hate the sport.
"I do not want to include everyone at the UCI because I believe that there are many, maybe most that work at the UCI, that are dedicated to cycling, they do it out of the love of the sport, but you and your buddy Hein have destroyed the sport.
"The sport does not need Pat McQuaid or Hein Verbruggen -- if this sport is going to change it is now. Not next year, not down the road, now! Now or never!"
The UCI refused to comment on LeMond's statement when contacted by CNN. The Union is preparing for a meeting on Friday during which it will discuss possible reforms in the wake of the Armstrong scandal.
LeMond's comments are sure to intensify the pressure on McQuaid and the UCI after it was revealed they failed to pick up signs of doping in Armstrong despite testing him over 200 times.
McQuaid has insisted a $100,000 donation from Armstrong to the UCI in 2002, revealed in USADA's report, was not part of a cover-up.
"UCI has nothing to hide in responding to the USADA report," McQuaid told reporters at a press conference last week. "Don't try to make the connection between the suspicious test and the donation. There were no positive tests from him."
But LeMond insists McQuaid is a barrier to change within the sport, and he called on people to donate to a fund to help Kimmage fight his legal battle with the UCI, who he accused of corruption.
"I have a file with what I believe is well-documented proof that will exonerate Paul," LeMond added. "I would encourage anyone that loves cycling to donate and support Paul in his fight against the Pat and Hein and the UCI.
"People that really care about cycling have the power to change cycling -- change it now by voicing your thought and donating money towards Paul Kimmage's defense.
"If people really want to clean the sport of cycling up all you have to do is put your money where your mouth is."
As McQuaid and the UCI prepare for Friday's meeting in Switzerland, the president acknowledged events of the past fortnight had sparked a period of introspection within the governing body.
"It's up to the UCI to look at the sport, look at team structures, look at race structures and try to create an environment for this to not happen again," McQuaid said in quotes reported by the AFP news agency.
"We want to take what we can learn from it and put in place measures to make sure it doesn't happen again."
McQuaid hinted the UCI might ask teams that participate in cycling's main competitions to donate more money to the anti-doping fight.
He also suggested the UCI will acquiesce to the Tour de France's wish not to reassign Armstrong's seven consecutive victories between 1999-2005 after it was described as a "lost decade" by race organizer Christian Prudhomme.
"It's up to us to come out of this affair and show everyone that we do see this as a crisis but also as an opportunity, because there is a danger that it could have a fatal effect on the sport, and I don't want that to happen," McQuaid added.
Elsewhere on Thursday, Team Sky -- who led Bradley Wiggins to victory in the 2012 Tour de France -- confirmed coach Bobby Julich had left his position.
Sky have asked their staff to sign a statement declaring they have had no previous involvement in doping but Julich, who was a teammate of Armstrong in 1995 and 1996, has admitted to using the blood-boosting agent EPO as a rider.
"Bobby has shown courage in admitting to the errors he made long before his time with Team Sky," Team Principal Dave Brailsford said on the team's official website.
"We understand that this is a difficult step for him and we've done our best to support him."