Right-wing British historian David Irving, who once famously said that Adolf Hitler knew nothing about the systematic slaughter of 6 million Jews, has been arrested in Austria on a warrant accusing him of denying the Holocaust.

Irving, 67, was detained Nov. 11 in the southern province of Styria on a warrant issued in 1989 under Austrian laws making Holocaust denial a crime, police Maj. Rudolf Gollia, a spokesman for the Interior Ministry, said Thursday.

Austrian media said the charges stemmed from speeches Irving delivered that year in Vienna and in the southern town of Leoben.

In a statement posted on his Web site, Irving's supporters said he was arrested while on a one-day visit to Vienna, where they said he had been invited "by courageous students to address an ancient university association."

Despite precautions taken by Irving, he was arrested by police who allegedly learned of his visit "by wiretaps or intercepting e-mails," the statement alleged. It said that en route to Austria, Irving had privately visited German playwright Rolf Hochhuth, a friend he had not seen in 20 years.

Hochhuth has gained notoriety for plays criticizing the Allies' bombing campaigns during World War II as war crimes and characterizing Winston Churchill as a war criminal. Earlier this year, Hochhuth was criticized for defending Irving as "an honorable man" and insisting he was not a Holocaust denier.

Austrian authorities had no immediate comment on the supporters' statement.

The Britain-based Holocaust Educational Trust congratulated Austrian authorities on the arrest. Trust chairman Lord Greville Janner, noting that Britain has no such laws that make denying the Holocaust a crime, praised the Austrians "for doing what our law should but does not permit."

"I hope this will lead to a successful prosecution," Janner said.

Irving in the past has faced allegations of spreading anti-Semitic and racist ideas. He is the author of nearly 30 books, including "Hitler's War," which challenges the extent of the Holocaust.

Besides his assertion that Hitler knew nothing about the Holocaust, he also has been quoted as saying there was "not one shred of evidence" that the Nazis carried out their "Final Solution" on such a scale.

The historian has said he does not deny that Jews were killed by the Nazis, but he challenges the number and manner of Jewish concentration camp deaths.

He has questioned the use of large-scale gas chambers to exterminate the Jews and has claimed that the numbers of those who perished are far lower than those generally accepted. He also contends that most Jews who died at Auschwitz did so from diseases like typhus, not gas poisoning.

Irving remained in custody Thursday at a prison in Graz, 120 miles south of Vienna, the Austria Press Agency reported, although that could not be confirmed.

If formally charged, tried and convicted, he could face up to 20 years in prison, said Otto Schneider of the public prosecutor's office.

But Schneider said it was unclear whether there were sufficient legal grounds to continue holding Irving on such a charge so many years after the alleged offense was committed. A decision was expected by the end of next week on how to proceed, Schneider said.

In March, more than 200 historians from around the world petitioned C-SPAN to cancel a project that would have included a speech by Irving as a counterpoint to a lecture by Deborah Lipstadt, a renowned Holocaust expert at Emory University.

Irving once sued Lipstadt for libel for calling him a Holocaust denier, but his lawsuit was dismissed in 2000 by a British court, which ruled that Irving was anti-Semitic and racist and misrepresented historical information.

His film, "The Search for the Truth in History," triggered protests in Australia that led organizers of the Melbourne Underground Film Festival to cancel a screening.

Irving has had numerous run-ins with the law over the years. In 1992, a judge in Germany fined him the equivalent of $6,000 for publicly insisting the Nazi gas chambers at Auschwitz were a hoax.