The head of international cycling has responded to increasing pressure on his position by accusing the man at the top of the World Anti-Doping Agency (WADA) of "blatant and aggressive" untruths.
The International Cycling Union (UCI) has been plunged into fresh controversy for disbanding its own inquiry into the Lance Armstrong drugs scandal.
The UCI's Irish president Pat McQuaid has been personally criticised but he hit back by accusing WADA president John Fahey of having a "personal vendetta" against cycling.
McQuaid said: "I am very saddened that it has come to this, but I cannot allow the latest blatant and aggressive misrepresentations contained in WADA's most recent press release to go unchallenged. Mr Fahey is saying one thing in public and quite the opposite in correspondence with me.
"The UCI is perplexed that WADA has now chosen to rebuff and attack the UCI's willingness to establish a truth and reconciliation commission, having just demanded that the UCI establish exactly such a commission. We have now reached this sorry juncture because WADA publicly questioned the independence of the independent commission.
"I would therefore urge the president of WADA one more time to try to set his personal vendetta and crusade against cycling aside and to support the UCI in doing what is right for cycling. Our aims are the same: to rid cycling and indeed all sports of the scourge of doping."
The UCI's decision to terminate the independent commission - whose members include Baroness Tanni Grey-Thompson - followed weeks of wrangling with WADA over its powers and whether those who testified could receive an amnesty.
The central issue of the inquiry concerned two donations by disgraced drugs cheat Armstrong to the governing body, and whether there was any complicity by the UCI in covering up his doping. The UCI announced on Monday it was scrapping the inquiry in favour of a 'truth and reconciliation' process. McQuaid claimed WADA had agreed to this - something denied by the agency.
Fahey said: "The UCI has again chosen to ignore its responsibility to the sport of cycling in completing such an inquiry and has determined to apparently deflect responsibility for the doping problem in its sport to others.
"UCI has publicly announced that WADA has agreed to work with it on some form of truth and reconciliation. This is not only wrong in content and process, but again deceitful. WADA has not and will not consider partaking in any venture with UCI while this unilateral and arrogant attitude continues."