With the cycling season kicking into high gear, the strongest

doping allegations yet against Lance Armstrong surfaced Thursday in

a barrage of detailed messages from Floyd Landis, the disgraced

rider and former teammate who finally confessed to years of

cheating himself.

In a series of e-mails sent to sponsors and sports officials,

Landis alleged Armstrong not only joined him in doping but taught

others how to beat the system and paid the former president of the

International Cycling Union to keep a failed test quiet.

"We have nothing to hide," Armstrong said at an impromptu news

conference before the fifth stage of the Tour of California.

"Credibility," the seven-time Tour de France winner said in

Visalia. "Floyd lost his credibility a long time ago."

In two e-mails obtained by The Associated Press, Landis also

admitted for the first time what had long been suspected - that he

was guilty of doping for several years before being stripped of his

2006 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."

Neither Landis nor his family returned repeated messages from

the AP.

The Wall Street Journal first reported the details of the

e-mails on its website early Thursday.

Landis alleged that Armstrong and longtime coach Johan Bruyneel

paid former UCI president Hein Verbruggen to cover up a test in

2002 after Armstrong purportedly tested positive for the

blood-boosting drug EPO. The UCI denied changing or concealing a

positive test result.

In an e-mail Landis sent to USA Cycling chief Steve Johnson, he

said Armstrong's positive EPO test was in 2002, around the time he

won the Tour de Suisse. Armstrong won the Tour de Suisse in 2001

and did not compete in 2002.

"We're a little confused," Armstrong said.

The e-mail to Johnson also said: "Look forward to much more

detail as soon as you can demonstrate that you can be trusted to do

the right thing."

Landis also implicated at least 16 other people in various

doping acts, including longtime Armstrong confidant George

Hincapie, Olympic medalist Levi Leipheimer and Canadian cyclist

Michael Barry.

The Wall Street Journal reported another e-mail from Landis also

linked another top American racer, Dave Zabriskie, to doping.

"At the end of the day, he pointed the finger at everybody

still involved in cycling, everybody that's still enjoying the

sport, everybody that still believes in the sport, everybody that's

still working in the sport, was in the crosshairs," Armstrong

said. "Yes, I'm standing here with all you guys because I won the

Tour de France seven times."

Landis said he was asked at one point to stay in an apartment

where Armstrong was living in 2003 and check the temperature in a

refrigerator where blood was being stored for future transfusions.

"Mr. Armstrong was planning on being gone for a few weeks to

train he asked me to stay in his place and make sure the

electricity didn't turn off or something go wrong with the

referigerator," Landis wrote.

Landis is part of a long list of former Armstrong teammates and

former U.S. Postal Service riders who have either acknowledged or

been caught doping.

Frankie Andreu has said he used EPO while preparing for the Tour

de France on Armstrong's team in the late 1990s. Olympic gold

medalist Tyler Hamilton tested positive after the 2004 Athens

Games, kept his medal on what amounted to a technicality, then

retired last year after telling the AP he knowingly took a banned

steroid. Roberto Heras was stripped of his win at the Spanish

Vuelta in 2005 and Spanish rider Manuel Beltran was kicked out of

the Tour de France, both found to have used EPO.

Hincapie said he was "really disappointed" by the allegations.

Jim Ochowicz, a former top USA Cycling official - who was also

implicated by Landis - defended himself and Hincapie.

"These allegations are not true, absolutely unfounded and

unproven," said Ochowicz, now the president of BMC Racing,

Hincapie's current team. "This is disappointing to anyone who

works in the sport or is a fan of the sport."

Johnson said USA Cycling would not comment about Landis' series

of e-mails, citing its policy on not discussing "doping

allegations, investigations or any aspect of an adjudication

process." The U.S. Anti-Doping Agency also declined comment for

similar reasons.

More accusations from Landis could be coming, however. In his

e-mail to Johnson, Landis indicated he has several diaries

detailing other experiences.

Until about 2005, Armstrong worked extensively with Michele

Ferrari, an Italian doctor who was linked to numerous doping

issues, but was cleared by an appeals court in 2006. Landis claimed

Ferrari extracted "half a liter of blood" from him in 2002, so he

could have it transfused during the Tour de France.

"Mr. Armstrong was not witness to the extraction but he and I

had lengthy discussions about it on our training rides during which

time he also explained to me the evolution of EPO testing and how

transfusions were now necessary due to the inconvenience of the new

test," Landis wrote.

Andy Rihs, the owner of the Phonak team for which Landis rode

when he won the Tour, issued a statement saying Landis' claims were

"lies" and a "last, tragic attempt" to get publicity. In one of

his e-mails, Landis alleges that Rihs was aware of his doping and

helped fund it.

Like Armstrong, UCI president Pat McQuaid questioned Landis'

credibility.

"He already made those accusations in the past," McQuaid said.

"Armstrong has been accused many times in the past but nothing has

been proved against him. And in this case, I have to question the

guy's credibility. There is no proof of what he says. We are

speaking about a guy who has been condemned for doping before a

court."

Armstrong said Landis threatened long ago to go public with

these allegations. He finally told him to do whatever he felt was

necessary.

"This is a man that's been under oath several times and had a

very different version," Armstrong said. "This is a man that

wrote a book for profit that had a completely different version.

This is somebody that took, some would say, close to $1 million

from innocent people for his defense under a different premise. Now

when it's all run out, the story changes."

Later Thursday, Armstrong crashed in the stage near Visalia,

Calif., abandoning the race and needing stitches and X-rays. It

wasn't immediately clear if the wreck would impact plans for the

Tour de France and challenging rival-turned-teammate-turned-rival

Alberto Contador, the defending champion of the race the Texan once

dominated with relative ease.