Landis' attorneys say the cyclist's positive doping tests could be invalidated because the same technicians were allowed to work on both samples. Lab rules prohibit technicians from participating in both tests to prevent them from validating their own findings.
The lawyers want the technicians from the French lab to be questioned for his arbitration case against the U.S. Anti-Doping Agency, scheduled for May 14.
"It's something we've been aware of for a while, but we've been trying to get more information about it," Landis' attorney, Howard Jacobs, said Friday. "It's part of the discovery fight we've been involved in."
Landis and his attorneys are focusing on this possible violation because a similar error at the Chatenay-Malabry lab outside Paris in 2005 resulted in the dismissal of doping charges against Spanish cyclist Inigo Landaluce.
"Given the gravity of this and now that there's precedent in the Landaluce case, we want to talk to both those operators," Landis spokesman Michael Henson said. "We don't know if it's as extensive as in the Landaluce case, but it's enough to peak interest."
The new allegation was first reported by the Los Angeles Times.
Landis' urine sample was found to contain elevated testosterone to epitestosterone levels after a 17th-stage win in last year's tour. He risks being the first rider in the 104-year history of the race to be stripped of his title.
Lab records reviewed by the Times showed technicians Esther Cerpolini and Cynthia Mongongu worked with the 'A' and 'B' tests of samples that resulted in Landis being accused of doping. The paper said the records weren't clear whether the women played significant enough roles in both tests to invalidate the findings.
A person familiar with the Landis case told AP that separate technicians handled Landis' A and B samples. The official requested anonymity because he was not authorized to speak about the case.
USADA general counsel Travis Tygart said he couldn't comment on specifics of an ongoing case.
"In every case, there's a search for the truth, and at the end of the day, it's a group of independent judges, not USADA, that makes a decision based on all the evidence of whether an athlete doped or not," Tygart said.
The charge of the same technicians handling both samples is the latest in a series of allegations brought by Landis' lawyers against anti-doping agencies and the French lab, as he attempts to overturn the positive tests and have his Tour victory upheld. Landis has argued the French lab that carried out the tests is unreliable, that the samples were contaminated and that he has been "subject to fundamentally unfair treatment by the anti-doping organizations and international sports federations."
The French anti-doping agency also has a case against Landis that could result in a two-year suspension, though a decision recently was postponed in exchange for Landis' agreement not to race in France again until 2008.
Associated Press Writer John Leicester in Paris contributed to this report.