France's national anti-doping agency (AFLD) on Wednesday offered to test allegedly suspect samples taken from US rider Lance Armstrong during the 1999 Tour de France.
Armstrong, the seven-time Tour de France winner, announced last month that he is to make a comeback after a three-year absence from the peloton.
During his career, the American has been accused of doping practices on several occasions, most notably in an article in French sports newspaper L'Equipe in 2005 after his retirement.
The daily newspaper claimed six urine samples from his 1999 Tour victory contained the banned blood-boosting drug EPO (erythropoietin) - claims strongly denied by Armstrong.
But AFLD said in a statement released on Wednesday: 'The way these samples are preserved and the volume of them mean that you can do an analysis for the possible presence of EPO on at least five stages of the 1999 Tour de France.
'AFLD offers Lance Armstrong an analysis of his samples from the 1999 Tour de France to prove his good faith.'
It added that 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.
