A notorious Holocaust denier who lived in Canada for decades before being deported to Germany to face prosecution has died, according to a statement from his wife Ingrid Zundel.

Ernst Zundel died Sunday at home in Germany after he was found unconscious by his sister Sigrid, the statement says.

Zundel was born in Germany, but later moved to Canada, where he operated a business and published Nazi propaganda before being convicted of "spreading false news" in 1985.

That conviction was overturned seven years later when the Supreme Court of Canada argued the charge violated Zundel's Charter right to freedom of expression.

Zundel would go on to live in Toronto's Cabbagetown neighbourhood for several years before a Federal Court ruled in 2005 that he was a national security threat, citing his connection with white supremacist and neo-Nazi groups. The move paved the way to his extradition.

In 2007, he was convicted in Germany of 14 counts of incitement of racial hatred and received a five-year sentence, the maximum allowable under the law.​ Having received credit for time served before trial, Zundel was freed in 2010.

Sunday's statement said Zundel reportedly died of a heart attack at the home where he was born in Germany's mountainous Black Forest region.

As news of the death broke, Bernie Farber, former chief executive officer of the Canadian Jewish Congress, told CBC News that Zundel had denied the genocide of "six million Jewish men, women and children."

"He brought terrible anguish to those few who survived the evil of the Shoah," Farber said, referring to the Holocaust. "Jewish tradition demands that we do not defame the dead."