Floyd Landis has said he has been offered a reduced sentence for doping if he gives "incriminating evidence" against Lance Armstrong.
Landis said the offer "speaks of the character" of the prosecution
Landis, who won 2006 Tour de France only to fail a drugs test, said the US Anti-Doping Agency made the offer.
The American said the USADA told his lawyer he would get "the shortest suspension they've ever offered" if he gave up "information" on Armstrong.
"I don't think that offer justified a response," said the 31-year-old rider.
"I didn't do what I am accused of doing and none of this has anything to do with Lance," he said, adding that he had not spoken to the seven-time Tour de France winner about the USADA's approach.
USADA's general counsel Travis Tygart, the man Landis said made the offer, told Reuters that legal rules meant he could not discuss matters related to the case.
But Tygart added: "If Mr Landis wishes to waive the rules and allow USADA to comment I will be more than happy to address his nonsense - otherwise I can't comment."
If his guilt is confirmed by a 10-day USADA arbitration hearing that starts in California on Monday, Landis faces a two-year suspension and the possibility of becoming the first Tour winner to be stripped of his title for doping.
The WADA-USADA system has proven to be an insult to the principles of justice - and no accused athlete has any chance of receiving a fair hearing
Armstrong and Landis are former team-mates who fell out in 2004, but Armstrong has recently backed Landis and been a critic of the way anti-doping agencies operate.
"I believe in Floyd, I believe he hasn't had a fair shake," said Armstrong, who had to deal with doping allegations throughout his career.
Landis tested positive for elevated levels of testosterone in a sample taken after he recovered from a poor day in the mountains to win the 17th stage of the Tour. That testosterone was later found to have come from an external source.
The Armstrong offer is the latest in a string of charges Landis has levied against USADA and the anti-doping authorities as he puts the final touches to his defence.
His lawyers have made the French laboratory that performed his test the focus of Landis's defence and have claimed that documents were mislabelled, specimens mishandled and the lab's findings inconsistent.
Landis is also furious about the flow of leaks to the media that have come from the lab.
"It has proven to be corrupt and incompetent at the same time," he said.
"The WADA-USADA system has proven to be an insult to the principles of justice. And no accused athlete has any chance of receiving a fair hearing."