NEW YORK — Disgraced American cyclist Floyd Landis has admitted to systematic use of performance-enhancing drugs and accused seven-time Tour de France champion Lance Armstrong of involvement in doping, The Wall Street Journal reported today.

Landis, who was stripped of his 2006 Tour de France title for doping but had always denied cheating, sent a series of e-mails to cycling officials and sponsors acknowledging and detailing his long-term use of banned drugs, the newspaper said.

The report said Landis wrote in the e-mails that he started doping in 2002, his first year racing with the U.S. Postal Service team led by Armstrong.

Landis also admitted to doping in an interview with ESPN.com.

Landis also accused American riders Levi Leipheimer and Dave Zabriskie and Armstrong's longtime coach, Johan Bruyneel, of involvement in doping, the Journal reported.

Armstrong is currently competing in the Tour of California and couldn't be reached for comment. Neither could Bruyneel, Leipheimer or Zabriskie.

The Journal said it had seen copies of three e-mails sent by Landis between April 30 and May 6, and that he had copied in seven people on the messages, including officials with USA Cycling and international governing body UCI.

Landis served a two-year ban after testing positive for elevated testosterone levels at the 2006 Tour. He was the first rider stripped of a Tour de France title.

"I want to clear my conscience," Landis told ESPN.com. "I don't want to be part of the problem any more."

He also said he was speaking out now in part because the World Anti-Doping Agency's eight-year statute of limitations was close to running out.

"If I don't say something now then it's pointless to ever say it," Landis said.

UCI president Pat McQuaid questioned Landis' credibility in a telephone interview Thursday with The Associated Press.

"What's his agenda?" McQuaid said. "The guy is seeking revenge. It's sad, it's sad for cycling. It's obvious he does hold a grudge."

McQuaid said he received copies of the e-mails sent by Landis to the U.S. cycling federation, but declined to comment on their contents. He said Landis' allegations were "nothing new."