Disgraced Tour de France winner Floyd Landis has sent a series of e-mails to cycling officials and sponsors admitting to the use of performance enhancing drugs, the Wall Street Journal reported on Thursday.
The report said the American's e-mails detailed his systematic use of the drugs during his career.
In an interview with ESPN.com late on Wednesday, Landis admitted using performance-enhancing drugs for most of his career, including during the 2006 Tour de France, which he won but was stripped of after failing a dope test.
"I want to clear my conscience," the 34-year-old told ESPN. "I don't want to be part of the problem any more."
The World Anti-Doping Agency's (WADA) statute of limitations for doping offences is eight years and that was also part of the equation, Landis said.
"Now we've come to the point where the statute of limitations on the things I know is going to run out or start to run out next month. If I don't say something now then it's pointless to ever say it," he said.
The Wall Street Journal said it has reviewed three emails sent earlier this year.
"Mr. Landis copied seven people on these three e-mails, including officials with USA Cycling and the International Cycling Union (UCI)," the report said.
"Three people who have seen the emails and spoken to Mr. Landis about them say they are authentic."
However, the timing of the American's announcement was questioned by UCI president Pat McQuaid.
"He probably needed to get it off his chest. Why is he announcing it in the week of the Tour of California?" McQuaid told said. "He must have an agenda."
McQuaid added that Landis's fate is now in the hands of American anti-doping authorities.
"USADA (US Anti-Doping Agency) will now look into this," McQuaid said.
Landis, the first rider to be stripped of a Tour victory, had previously denied any wrongdoing but the Court of Arbitration for Sport (CAS) rejected his assertion that his positive test was due to procedural mistakes by the laboratory.
He said last year after his two-year ban ended that he is trying to decide whether to ride again in the Tour de France.
In February, a French judge issued an arrest warrant against Landis for suspected hacking into an anti-doping laboratory computer.
French anti-doping agency head Pierre Bordry said that the judge, Thomas Cassuto, believed Landis wanted to prove the laboratory where his samples were tested was wrong.