The World Anti-Doping Agency branded the UCI "deceitful" and "arrogant" on Tuesday after cycling's governing body shut down its own independent inquiry into doping.
WADA said that the UCI has "again chosen to ignore its responsibility to the sport" by disbanding the commission examining claims cycling leaders helped cover up suspicious doping tests given by Lance Armstrong and unethically accepted US$125,000 in donations.
The UCI is setting up a separate amnesty-style "truth and reconciliation commission" (TRC) that it claimed in a news release yesterday was supported by WADA President John Fahey.
"This is not only wrong in content and process, but again deceitful," WADA said in a statement. "The fact is that WADA was awaiting a reply to the correspondence when the UCI release was delivered.
"WADA has not and will not consider partaking in any venture with UCI while this unilateral and arrogant attitude continues."
But UCI President Pat McQuaid issued an angry response to the WADA statement, which he called "blatant and aggressive misrepresentations," and released private e-mail exchanges with the agency.
"The UCI is perplexed that WADA has now chosen to rebuff and attack the UCI's willingness to establish a TRC, having just demanded that the UCI establish exactly such a commission," McQuaid said in a statement.
McQuaid urged Fahey to set aside his apparent "personal vendetta and crusade against cycling" and support the TRC.
"Our aims are the same: to rid cycling and indeed all sports of the scourge of doping," McQuaid said.
"The UCI is determined not to dwell on WADA's inconsistent behavior," he added. "We wish to reaffirm our commitment to establishing the TRC."
McQuaid claimed that Fahey supported the independent panel being replaced by a TRC, and released an e-mail that included the anti-doping chief saying the "process should start over from a new beginning."
But WADA earlier today said publicly that it would not "pay for or contribute to any collaborative effort with UCI into investigating UCI's long-standing problems with doping in its sport and its alleged complicity."
Accusations against the UCI emerged in the US Anti-Doping Agency report that led to Armstrong being stripped of his seven Tour de France titles and eventually confessing to doping after years of denials.
In justifying the reason to disband the independent panel, the UCI cited WADA's refusal to cooperate with the inquiry.
But WADA today said it would not participate with the commission because of the "inadequacies of the terms of reference and the timelines," including a demand that the UCI could not scrutinize or edit the findings before they were released.
WADA said it hopes the UCI's independent commission will still reconvene as previously planned on Thursday - despite being disbanded. The three-person body complained today that the UCI never provided the cooperation - promised by UCI President Pat McQuaid - to allow it to function.
"This failure to cooperate makes our task impossible," the commission, which was chaired by British judge Philip Otton, said in a statement. "Therefore, the proposed hearing on (January 31) will not take place."