France's anti-doping chief has proposed that Lance Armstrong agree to a retesting of urine samples from his first Tour de France win to determine whether they show traces of EPO.

The samples, which date from 1999, are frozen in France's drug testing laboratory in the suburbs of Paris.

They've been a source of controversy since French sports newspaper L'Equipe reported in 2005 that a new round of tests on the samples found EPO, a blood-boosting hormone that enhances endurance.

Armstrong, now making a return to cycling after retiring in 2005, has always insisted that he never doped.

He said he was the victim of a "witch hunt" when L'Equipe's story came out in 2005, a month after the last of his record seven Tour wins.

"I want this comeback to take place in the best circumstances," Pierre Bordry, head of the French anti-doping agency, was quoted as saying in the L'Equipe.

"With this in mind, I propose - if he agrees - a new complete analysis of these six samples taken at the 1999 Tour and which contain erythropoietin (EPO)."

"This way, he will perhaps have the chance to affirm that he never cheated during his brilliant career," Bordry said.

A Dutch lawyer appointed by cycling's governing body cleared Armstrong after L'Equipe's 2005 allegations.

But Dick Pound, who then headed the World Anti-Doping Agency, said those findings were full of holes.

Bordry is now proposing that the samples be tested again - in another WADA-accredited European lab outside of France if Armstrong prefers.

Bordry said he wants to be "a referee in this affair which sets the investigation by L'Equipe against the version of Lance Armstrong."

"If he agrees, we'll launch the operation," Bordry said.

Bordry called Armstrong a "great champion" and said he understands his desire to return to the Tour.

The cancer survivor is using his comeback to focus attention on the fight against the disease which nearly killed him.

Should the tests come back positive, there could be no anti-doping disciplinary procedures against Armstrong because of the eight-year moratorium on doping offences.