Ernst Zündel sits in a court in Mannheim, Germany, in 2005. (Michael Probst/AP)

Ernst Zündel, a far-right activist who rose to notoriety over decades of public neo-Nazi activity in Canada and the United States before being deported to his native Germany on Holocaust denial charges, has died. He was 78.

Marina Lahmann, a spokeswoman for the community of Bad Wildbad in Baden-Württemberg where Mr. Zündel lived, told the Associated Press that Mr. Zündel died over the weekend. She had no further information, saying the paperwork had not yet been processed.

The news media in Canada quoted a statement from his wife, Ingrid Zündel, saying that he died of a heart attack at his home Aug. 6.

Born in Germany in 1939, Mr. Zündel immigrated to Canada in 1958 — allegedly to avoid German military service — and lived in Toronto and Montreal until 2001.

He achieved international notoriety for his neo-Nazi beliefs and writings, including “The Hitler We Loved and Why,” and operated Samisdat Publishers, a leading distributor of Nazi and Nazi-era propaganda. He also provided regular content for an eponymous far-right website.

Canadian officials rejected his attempts to obtain citizenship in 1966 and 1994.

After leaving Canada, he moved to Pigeon Forge, Tenn., where he had married fellow right-winger Ingrid Rimland.

In 2003, he was deported to Canada for alleged immigration violations. After he arrived in Toronto, he was arrested and held in detention until a judge ruled in 2005 that his activities posed a threat to national and international security and he was deported to Germany, where he was being sought for Holocaust denial.

Denial of the Holocaust is illegal in Germany. Because Mr. Zündel’s Holocaust-denying website was available in Germany, he was considered to have been spreading his message to Germans.

Mr. Zündel, who portrayed himself as a peaceful campaigner being denied the right to free speech, was convicted in Mannheim in 2007 of 14 counts of inciting hatred for engaging in years of anti-Semitic activities and sentenced to five years in prison.

After he served his sentence, a crowd of some 20 supporters clapped and shouted “Bravo” as he was released from prison in Mannheim in 2010.

Outside the prison, he refused to comment on his beliefs about the Holocaust, saying only that “it’s kind of a sad situation, there’s a lot to say,” before adding, “I’ll certainly be careful not to offend anyone and their draconian laws.”