Right-wing British historian David Irving was convicted in Austria on Monday of denying the Holocaust - a crime in this country once run by the Nazis - and sentenced to three years in prison. Irving, who had pleaded guilty and insisted during his one-day trial that he had had a change of heart and now acknowledged the Nazis' World War II slaughter of 6 million Jews, had faced up to 10 years behind bars for the offense. Before the verdict, Irving conceded he had erred in contending there were no gas chambers at the Auschwitz concentration camp. Irving's lawyer immediately announced an appeal against the sentence. "I made a mistake when I said there were no gas chambers at Auschwitz," Irving testified, at one point expressing sorrow "for all the innocent people who died during the Second World War." Irving, 67, has been in custody since his arrest in November on charges stemming from two speeches he gave in Austria in 1989 in which he was accused of denying the Nazis' extermination of 6 million Jews.