Seven -time Tour de France winner Lance Armstrong has faced several doping claims, especially from ex-associates. The latest in the list is former team-mate Tyler Hamilton who claimed Armstrong used the performance-enhancing drug EPO.

Hamilton, who was a part of Armstrong's first three Tour de France winning postal squads, has now said they both used EPO during the 1999 Tour. Armstrong defended himself on his twitter page saying, Never a failed test. I rest my case.

Hamilton, in CBS program '60 minutes', said, I saw (EPO) in his refrigerator. I saw him inject it more than one time, like we all did. Like I did, many, many times.

However, Armstrong's spokesman Mark Fabiani denied the claims and accused Hamilton of attempting to gain publicity for his book. Fabiani said in a statement, Hamilton is actively seeking to make money by writing a book, and now he has completely changed the story he has always told before so that he could get himself on '60 Minutes' and increase his chances with publishers.

But greed and a hunger for publicity cannot change the facts - Lance Armstrong is the most tested athlete in the history of sports. He has passed nearly 500 tests over 20 years of competition.

The US Postal team has faced many allegations of the use of banned substances before and is currently the subject of a federal investigation in the United States.In 2010, Floyd Landis, another ex-team mate of Armstrong, had also accused him doping.