A French judge has issued an international arrest warrant against American rider Floyd Landis for suspected hacking into an anti-doping laboratory computer, French anti-doping agency head Pierre Bordry told Reuters on Monday.

In an interview, Bordy said the judge Thomas Cassuto believed Landis, whose 2006 Tour de France title was stripped after he failed a dope test, wanted to prove the laboratory where his samples were tested was wrong.

"French judge Cassuto from the Tribunal de Grande Instance of Nanterre informed us that he had issued an international arrest warrant on Jan. 28 against Floyd Landis, who tested positive for banned testosterone during the 2006 Tour de France, after our laboratory computer system was hacked," Bordry said.

"He was summoned by the judge, he didn't come so he's now under an international arrest warrant."

The French anti-doping agency launched legal action against unnamed persons after they found their laboratory computer system had been hacked into in September 2006.

Landis, the first rider to be stripped of a Tour victory, has continually denied any wrongdoing but the Court of Arbitration for Sport (CAS) has rejected his assertion that his positive test was due to procedural mistakes by the laboratory.

Landis, 34, said last year after his two-year ban ended that he was trying to decide whether to follow fellow-American Lance Armstrong's example and ride again in the Tour de France.

"It seems that (Landis) made all he could to enter into our computer system to try to prove the laboratory was wrong. He showed many documents he got by hacking to numerous sporting instances," Bordry said. "The judge traced a network of hackers back to the ringleader."