He is back in the UK after his release on probation from a three-year jail term imposed in Austria for denying the Holocaust in a 1989 speech. "Stalinist legislation" had put him in prison for expressing the "wrong views", Irving told the BBC.

After 400 days in jail, "you've earned the right to show no remorse", he said. "Not showing remorse is not a criminal offence."

Irving's reputation as a credible historian is ruined.

"Austrian law is a very odd kind of legal system - it's nothing like the English legal system. You're required to show remorse, you're required to confess, you're required to admit guilt otherwise everything will be tripled."

The conviction had sparked intense debate, with supporters saying it was justified but opponents arguing it undermined freedom of speech.

In his speech in Austria 17 years ago, he denied the existence of gas chambers at Auschwitz, though he later said he was "mistaken".

He told his initial trial that Auschwitz's role as a "killing centre" has been exaggerated to pander to the tourist trade.

At a London news conference on Friday, Irving said he had been treated "with utmost contempt" in Austria and Germany. He called for an international boycott of all historians in the nations until they put pressure on their governments to change laws.

The 68-year-old insisted he was not a "Holocaust denier". "For the last 15 years, I have made no bones at all about the fact that the Nazis killed millions of Jews in different methods around the world, around their empire, particularly on the eastern front, " he said.

Irving served 13 months of his sentence and has now been banned from Austria.