BERLIN (Deutsche Presse-Agentur) -- U.S. cyclist Floyd Landis has admitted to doping and said many of his top competitors, including seven-time Tour de France champion Lance Armstrong, also used banned performance-enhancing drugs, according to media reports Thursday.

Wall Street Journal reported that Landis, who was stripped of his 2006 Tour de France title after failing a doping test, had sent a series of emails to cycling officials and sponsors admitting to the use of performance-boosting drugs.

ESPN.com late Wednesday quoted Landis as saying he had used performance-enhancing drugs for most of his career, including during the 2006 Tour de France.

"I want to clear my conscience. I don't want to be part of the problem any more," the 34-year-old told ESPN.

"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."

Pat McQuaid, president of the International Cycling Union UCI, said he was one of the officials to receive the e-mails but told German Press Agency dpa Landis had "no credibility" and was "seeking revenge."

McQuaid said all the documents were with the UCI's legal department but the governing body was not planning to talk to Landis about the accusations.

The Wall Street Journal report said Landis's emails, of which it had seen three, detailed his systematic use of the drugs during his career.

"Mr Landis copied seven people on these three emails, including officials with USA Cycling and the International Cycling Union," it said.

The report said that in one of the emails, dated April 30 and addressed to Stephen Johnson, the president of USA Cycling, Landis said that Armstrong's coach, Johan Bruyneel, introduced him to the use of steroid patches, blood doping and human growth hormone in 2002 and 2003, his first two years on the US Postal Service team.

He alleged Armstrong helped him understand the way the drugs worked.

The report said Landis's charges could not be independently verified and that he did not respond to a request for comment. Armstrong had also not responded to requests for comment.

Landis became the first rider to be stripped of a Tour de France victory but had previously always denied any wrongdoing.

The Court of Arbitration for Sport (CAS) rejected his appeal against a two-year ban when he claimed his positive test for testosterone was due to procedural mistakes by the laboratory.

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