Floyd Landis claimed Sunday that electronically stored data from disputed dope tests conducted on his 2006 Tour de France stage 17 samples had been destroyed at a French laboratory.

Simon Davis, a technical consultant for Landis, told the cyclist that "critical evidence stored as electronic data files had been erased from the hard drive and the original data destroyed at the Laboratoire National de Depistage du Dopage (LNDD)," according to a release issued by Landis spokesman Michael Henson on Sunday.

"The existing data bears indication of alteration," the release said.

Davis was at the LNDD last Thursday, along with representatives of the US Anti-Doping Agency (USADA), to witness the extraction of the data files by an independent expert commissioned to retrieve and analyze the files.

The files were electronically preserved records of the Isotope Ratio Mass Spectrometry tests conducted on Landis' stage 17 samples.

Landis won the Tour de France in dramatic fashion last year, rebounding from a spectacular collapse on stage 16 to cap a 130km breakaway with victory on stage 17.

It was after stage 17 that one sample from the American cyclist tested positive for elevated levels of the male sex hormone, which is produced in the body but which also exists in a synthetic form.

In fighting the doping charge, which could cost him the Tour title as well as a ban, Landis has repeatedly charged the LNDD of mishandling his samples.

In the case of the electronic data, Landis said that the LNDD, prior to the arrival of the independent expert and Davis, had destroyed the original electronic files of the relevant test results, "exposing the files to potential tampering."

Landis' charge comes in the wake of a report in the French newspaper L'Equipe that re-tests of some of his samples from the race - ordered by USADA - had shown evidence of synthetic testosterone. The samples had passed the traditional testosterone/epitestosterone ratio test, but the paper reported that the more rigorous carbon-isotope-ratio test triggered positive results. On Sunday Landis again blasted USADA for allowing the testing of previously cleared samples, and for denying him access to evidence in the case against him.

Facing a hearing in his case on May 14, Landis said he was considering an appeal to the U.S. Department of Justice to investigate the use of government funds in the adjudication of his anti-doping proceedings.

"I have every confidence that they can determine if any misuse of federal funds and any resulting criminal activity has taken place on the part of USADA in my case," he said.