British historian David Irving, who began last week serving a three-year prison sentence in Austria for Holocaust denial, repeated Tuesday earlier claims that he does not believe Hitler systematically worked to annihilate European Jewry.

In an attempt reduce his prison sentence, Irving claimed during his trial that he had changed his mind since comments he made in 1989 - for which he was convicted - and insisted he believes today that the Holocaust indeed took place and that there were gas chambers at Auschwitz.

Speaking from his Austrian prison cell, Irving told the BBC that he now believes Jews were exterminated in gas chambers in some instances, including 1.4 million that were killed in Treblinka and Sobibor. However, he said he thinks that the number of Jews killed at Auschwitz is smaller than commonly believed, and that there were only two "small" gas chambers at the camp.

Responding to a question about the whether he thinks there was a systematic plan by Hitler to exterminate all Jews, Irving told the BBC, "That is absolutely wrong and nobody can justify that... Adolf Hitler's own involvement in it has a big question mark behind it."

"Given the ruthless efficiency of the Germans, if there was an extermination program to kill all the Jews, how come so many survived?" he asked the BBC.