Lance Armstrong and the United States Anti-doping Agency remain in conflict over the disgraced cyclist's insistence he did not use performance-enhancing drugs in the final part of his career.

The 41-year-old recently admitted to doping during each of his seven Tour de France triumphs, from 1999 to 2005, but claims he did not during his comeback from retirement, in 2009 and 2010.

Evidence in the USADA report suggests Armstrong is not being truthful about his comeback years following his televised confession to Oprah Winfrey. Travis Tygart, USADA's chief executive, insists there was scientific proof.

Tim Herman, Armstrong's lawyer, said: "I can only say that Lance is absolutely telling the truth about 2009-10.

"Proving a negative is very difficult. However, the information USADA relies upon came from Lance's own website.

"It was posted there by him. I am not a statistical expert, but I have been told the conclusion of Mr Tygart is incorrect."

In his interview with Winfrey, Armstrong insisted he had stuck to a pact made with former wife Kristin that he would not dope during his comeback to cycling.

USADA revealed last year that Armstrong had led "the most sophisticated, professionalised and successful doping programme sport has ever seen".

The UCI, cycling's world governing body, stripped Armstrong of his seven Tour titles - none of which were reassigned - and he was banned from sport for life.

Tygart claimed there were clear reasons for Armstrong, who was competing in triathlons, mountain bike events and marathons prior to his ban, to proclaim his innocence during those later years as it meant he would be exempt from possible criminal prosecution, because there is a five-year statute on a charge of fraud.

"The evidence is clear," Tygart told CBS' 60 Minutes programme.

"His blood tests in 2009, 2010, expert reports based on the variation of his blood values from those tests, one to a million chance that it was due to something other than doping."

USADA have given Armstrong a deadline of February 6 to agree to confess all under oath.

Armstrong told Winfrey he would "be the first man through the door" to take part in a truth and reconciliation hearing.

Herman insists his client is prepared to partake in the procedure.

In a letter to the USADA lawyer, prior to the broadcast of Tygart's 60 Minutes interview, Herman wrote: "Lance's commitment to the truth and reconciliation process is firm, despite the attempt at piling on through more appearances by Mr Tygart on 60 Minutes."