Armstrong shocked the cycling world when he announced his comeback plan
The head of the French anti-doping agency believes Lance Armstrong has missed a chance to prove his critics wrong over allegations of drug use.
Pierre Bordry gave him the opportunity to have samples taken during the 1998 and 1999 Tours de France retested.
But the seven-time Tour champion refused to consent to the new tests.
"If the analysis is clean it would have been very good for him. But he doesn't want to do it and that's his problem," Bordry told BBC Sport.
"It was a good opportunity for him to answer positively to my proposition, because if he is clean, as he says, I am ready to follow him."
The American, who has always vigorously denied any wrongdoing, has announced he will return to the sport in 2009 after an absence of more than three years.
Armstrong, who would have to give his permission for tests on any sample older than eight years, gave a terse response to Bordry's invitation to prove he had "never cheated in his brilliant career".
"Unfortunately, Mr. Bordry is new to these issues and his proposal is based on a fundamental failure to understand the facts," the 37-year-old said in a statement that was released on Wednesday.
Scientifically there is no problem to analyse these samples - everything is correct
"In 2005, some research was conducted on urine samples left over from the 1998 and 1999 Tours.
"That research was the subject of an independent investigation, and the conclusions were the samples have not been maintained properly, have been compromised in many ways, and even three years ago could not be tested to provide any meaningful results.
"There is simply nothing I can agree to that would provide any relevant evidence about 1999."
The urine samples in question have been the subject of speculation ever since French newspaper L'Equipe reported in 2005 that six B samples contained the banned substance EPO - a blood-boosting hormone that enhances endurance.
Drug-testing protocol dictates that blood or urine is divided into A and B samples and both must show traces of the banned substance for a test to be declared positive. Cycling did not have a robust test for EPO until 2001.
Mark Higgins, a spokesman for Armstrong, told Thursday's L'Equipe: "He is not interested in discussing again results from samples taken in 1999. I will refer the AFLD to the Vrijman report."
This is the independent investigation Armstrong referred to in his statement. It was conducted by Dutch lawyer Emile Vrijman, cleared the Texan superstar of doping in 1999 and accused the French lab at Chatenay-Malabry of misconduct.
But Vrijman's report failed to satisfy everybody - World Anti-Doping president Dick Pound being a notable detractor - and Bordry has rejected Armstrong's claim that tests on the samples could not be trusted.
"Scientifically there is no problem to analyse these samples," he said. "They have been kept in good condition and we have enough quantity to do (the tests). Everything is correct."
Bordry added he had "no idea" why Armstrong, who he had not spoken to personally, refused to allow the retests.
"Most people think my agency plays fair," Bordry said. "We proposed a solution, he doesn't want it, so that's his problem, not mine."
Armstrong famously recovered from life-threatening cancer to dominate the Tour between 1999 and 2005. He has stated the primary reason for his surprise return to the saddle is a desire to raise awareness and funds for his cancer charity.
He has also declared he wants to set the record straight by publishing on the internet the results of a personal anti-doping programme, to be administered by leading American anti-doping expert Professor Don Catlin.
Bordry, however, was dismissive of this plan and said only the officially recognised anti-doping programmes of Wada, cycling's governing body the UCI, or the AFLD had any validity.
Armstrong confirmed last week he will ride for the Astana team run by his former race manager Johan Bruyneel, and hopes to start his comeback in Australia's Tour Down Under in January, although there are doubts about his eligibility for that race as he will not have been back on the anti-doping register the required six months.