World anti-doping chief Richard Pound has rejected a demand for an apology from an association of professional cyclists that says he has tarred all riders with his characterization of pro racing as a culture fraught with cheating and doping.

"The CPA [Cyclistes Professionnels Associés] has misunderstood, misconstrued, misinterpreted and mischaracterized the situation," the Montreal lawyer said yesterday, blasting back at a letter from the pro riders that insisted he publicly retract comments published late last year in the Guardian, a British newspaper.

The Switzerland-based group gave Pound, the chairman of the World Anti-Doping Agency, until Jan. 20 to apologize for comments in which he accused riders, teams, organizers and officials of supporting a culture of "deliberate cheating."

Pound has previously feuded with former International Cycling Union chief Hein Verbruggen over the sport's delay to opt in to the WADA code and revelations by a French sports paper that tests done years before on Tour de France riders linked American cycling star Lance Armstrong to the use of a banned blood-boosting substance.

"You have openly attacked the sport of cycling and its figures, claiming in particular the general existence of doping among cycling teams," the riders association wrote in a letter to Pound, excerpts of which were published yesterday in the Guardian.

"You publicly accuse all cyclists of acting against honour and sporting ethics, and branding them in the eyes of the public as cheaters bent of breaking the rules," the group said in demanding a public retraction. "Otherwise, the CPA could proceed by any means necessary."

The letter refers to an opinion piece written by Pound in October in which he called the problem of doping in cycling a "stunning indictment of failure on the part of officials, organizers and riders."

"Drug use, within entire teams continues unabated," Pound wrote. "It is planned and deliberate cheating, with complex methods, sophisticated substances and techniques, and the active complicity of doctors, scientists, team officials and riders. There is nothing accidental about it."

Pound said it was absurd to believe doping violations in the sport were occurring without direct assistance from many people.

"Using EPO [the performance-enhancing drug erythropoietin] and some of these things are pretty sophisticated doping activities," Pound told the Associated Press. "It's not just done by a cyclist acting on his own. I don't think there's a basis for their complaint."

But the riders disputed Pound's allegations, calling them "particularly serious, disrespectful and defamatory."

Pound accused world cycling's governing body, the International Cycling Union, of allowing doping to remain widespread.

"All this cheating goes on under the supposedly watchful eyes of cycling officials, who loudly proclaim that their sport is drug-free and committed to remaining so," Pound wrote. "Based on performance, they should not be allowed outdoors without white canes and seeing-eye dogs."

The governing body rejected the allegations and said it was seriously tackling banned substances in cycling.

Pound has been at the centre of much of the controversy in the cycling world since the French newspaper L'Équipe claimed in August that traces of EPO were found in a set of Armstrong's backup samples at the 1999 Tour de France.

Pound accused Verbruggen of leaking documents about the alleged positive tests to L'Équipe. Pound also questioned the union's willingness to fully investigate the allegations.

Verbruggen denied Pound's accusations and claimed WADA was blocking its investigation by withholding information.

Armstrong's agent and lawyer later criticized Pound, accusing the Canadian lawyer of smearing Armstrong in public without conclusive proof or due process.

Armstrong said he was concerned Pound might have been seeking revenge for an open letter he sent to newspapers and the WADA chief several years ago, defending his sport against the widely held notion that cycling was rife with performance-enhancing drugs.