Landis saw Armstrong dope

Landis, in his first interview since admitting doping during his career, told ABC's Nightline show that his former friend and team-mate had transfused his own blood.

"Rather than go into the entire detail of every single time I've seen it, yes, I saw Lance Armstrong using drugs," said Landis, who won the 2006 Tour de France but was later stripped of the title.

Asked whether he had seen Armstrong transfusing blood, he replied "yes". A second question asking if Armstrong has transfused blood more than once, the answer was: "Yes, many times".

Armstrong, seven-times Tour de France winner between 1999 and 2005, has always vehemently denied the accusations. He has never tested positive.

The 38-year-old's lawyer Tim Herman refuted the latest claims against his client, who he said has undergone 300 tests throughout his career.

"Landis is a confessed perjurer and he is a liar, and I think, as Lance said ... when you taste milk to see if it's sour, you take a first taste and you don't have to drink the whole carton to know it's all sour," Herman said.

Despite having never tested positive, Armstrong has been the target of doping allegations for much of his career. 

But that has not prevented him being admired by many fans for overcoming cancer before winning the Tour de France each year from 1999 to 2005.