Landis is determined to fight what he sees as an 'unjust' case

Tests on the samples at a laboratory in Paris concluded on Sunday with French paper L'Equipe reporting they showed traces of synthetic testosterone.

Landis's consultant Paul Scott was excluded from witnessing the tests, in the absence of two USADA experts.

Landis said it was "yet another in a series of malicious actions by USADA".

"How can I be expected to prove my innocence while USADA (the US Anti-Doping Agency) endeavours to break their own rules at every turn?" he questioned on his personal website.

"Together, they have turned this proceeding into a full-scale attack on my civil rights and a mockery of justice.

"I'm infuriated by the behaviour of USADA and the [French anti-doping lab] LNDD (Laboratoire National Depistage de Dopage)," he added.

The president of the French anti-doping agency, Pierre Bordry, confirmed the incident had taken place, but said it stemmed from a prior agreement stipulating that Landis's expert would attend the test with two USADA experts.

Scott was excluded on Sunday because the USADA representatives did not turn up, Bordry said.

We're looking at potentially deliberate falsification of results and wilful destruction of evidence Floyd Landis

"Such behaviour constitutes a clear and direct infringement of Landis's rights while casting severe doubt on the integrity of an already dubious process," Landis's spokesman Michael Henson said in a statement.

Seven samples taken during the 2006 Tour, which initially failed to produce positive findings, were retested at USADA's request at the laboratory at Chatenay-Malabry, the same one that revealed Landis's positive test for high levels of testosterone after he won the 17th stage of last year's Tour.

The results have not officially been made public yet, but L'Equipe reported the lab used a technique aimed at detecting exogenous testosterone (hormone artifically introduced to the body), rather than the male sex hormone naturally contained in the body.

Landis's lawyers had argued the re-testing was unnecessary because initial tests had been negative, while their client claimed the latest results reported by L'Equipe could have been falsified by the laboratory.

"I won the Tour fair and square, and I'm disappointed but not surprised to see the leak...to L'Equipe," Landis said.

"It's just another example that the very few rights an athlete has are being completely ignored by the anti-doping authorities," he added, accusing the LNDD and USADA of "a total lack of ethics".

"We're looking at potentially deliberate falsification of results and wilful destruction of evidence which was one of our arguments against retesting being done at the lab in question."

Landis has always vehemently denied any wrongdoing, but if found guilty of doping, he faces a two-year ban from the sport and the probability of becoming the first Tour winner to be stripped of his title.

He is due to have a separate USADA hearing on 14 May.