International Cycling Union president Pat McQuaid has called on his election rival Brian Cookson to condemn the "gangster politics" in an increasingly bitter election contest following the emergence of an anonymous leaked dossier alleging corruption at the UCI.
British Cycling president Cookson is challenging current UCI incumbent McQuaid for the leadership of the governing body, a process which is still in dispute after McQuaid failed to secure a nomination from either his home country, Ireland, or Switzerland, his current place of residence.
McQuaid now wants the UCI Congress to vote in a rule change to allow him to be nominated by Thailand and Morocco. A number of federations, including the United States, have asked for the UCI to take the dispute to the Court of Arbitration for Sport for a decision on whether that should be permitted.
McQuaid issued a strongly-worded statement in response to the corruption allegations, and has now written an open letter to all of the national cycling federations, in which he calls for Cookson to help protect the "democratic process" of electing a new leader.
The letter read: "The claims in this so-called dossier are a complete fabrication. They are totally untrue and are not supported by a scintilla of evidence.
"The UCI Ethics Commission has already tried to investigate this dossier
"This is a scurrilous and libellous attack on my character.
"This is not democracy. This is gangster politics.
"If Brian Cookson does not now condemn these tactics utterly, then we can only assume that he supports them.
"I am proud to stand before you as a candidate in this election. I am proud to present you with a clear choice of leadership for the coming four years.
"I will be prouder still if you choose me as your next President at Congress this month.
"But if you do not, I will accept your choice with good grace and I will leave Florence with my head held high.
"I will know that I have given my all to the UCI over the past eight years and that I have done everything possible to protect our democratic process.
"I challenge Brian Cookson to say the same thing."
Cookson has yet to respond to the McQuaid letter but is understood to be planning to write to the cycling federations himself later this week.
In a statement issued before McQuaid's letter was published, Cookson had called for a new investigation to be launched.
He said in a statement: "These allegations, which appear to be similar to those made to the UCI Management Committee in June, are clearly very serious.
"For the good of the UCI and cycling, they should be immediately and thoroughly investigated by the relevant authorities. I hope that this matter can be fully resolved before the UCI congress on 27 September.
"For my part, I remain totally committed to a democratic election under the constitution of the UCI and will continue to talk and listen to national federations and voting delegates on how, together, we can grow cycling globally and restore faith and trust in our sport."
The UCI Congress will elect the world governing body's next president at the World Road Championships on September 27 in Florence, Italy.
The election comes against the background of the Lance Armstrong doping scandal which erupted 12 months ago.