Landis won the Tour de France last July, largely due to an heroic effort on stage 17 of the race.

But it later transpired that he tested positive for a banned substance after that stage and he has been in cycling limbo ever since - suspended from racing and fighting to clear his name.

But now Landis has hit out at Pound for branding him as guilty before his case has been closed - he is appealing a ban.

"Dick Pound's recent defamatory and absurd public comments - in the midst of a process where the highest ethical standards should support a fair and just outcome - highlight the dramatic and systematic problems with global anti-doping enforcement and adjudication," said Landis.

Landis's response via a press release came a day after the New York Times published comments from Pound about Landis's case.

"He was 11 minutes behind or something, and all of the sudden theres this Herculean effort, where he's going up mountains like he's on a goddamn Harley," said Pound.

Landis's Tour-winning effort came just a day after his yellow jersey hopes had seemingly gone up in smoke as he cracked on the final climb of stage 16.

"It's a great story," added Pound. "Wonderful. But if it seems too good to be true, it probably is."

Turning to Landis's alleged testosterone results, which included a high testosterone-to-epitestosterone ratio, Pound said crudely: "I mean, it was 11 to 1! You'd think he'd be violating every virgin within 100 miles. How does he even get on his bicycle?"

But Landis has hit out against what he claims is misinformation coming from Pound.

"Mr. Pound's published reference to the testosterone in my system proves he has not even bothered to review the facts regarding the unsubstantiated allegations against me," said Landis.

"My testosterone levels were tested as normal following stage 17 of the 2006 Tour de France and this fact is clear to anyone who cares to review the lab data.

"Absolute testosterone levels are not even part of the allegations. The LNDD (Laboratoire National Depistage de Dopage - the French lab that tested Landis's sample) tested a clearly contaminated sample of my urine, against WADA rules, and even then my testosterone levels fell into the normal to low range.

"Mr. Pound should conduct himself in a manner more consistent with the seriousness of the unsubstantiated allegations against me and the damage they have caused to a great number of people."

Landis is not the only American Tour winner to have had a run in with Pound.

Record seven-time champion Lance Armstrong is a vocal critic of the WADA chief who has supported unproven allegations that he took performance-enhancing substances during his career.

Before his retirement, Armstrong was the most tested athlete in the world and never failed a drug test