Holocaust denier Ernst Zundel has died in Germany at the age of 78.

Zundel died Sunday at his home in Baden-Wuerttemberg, reportedly of a heart attack.

He served a five-year prison sentence in Mannheim, Germany after being found guilty in 2007 of inciting hatred against Jews and systematically denying the Nazi genocide against the Jews — in 14 specific instances — on his Web site and in a newsletter. His five-year sentence included two years in jail following his deportation from Canada in 2005. The trial began in November 2006. He left prison in 2010.

Born in Germany, Zundel left the country in 1958 allegedly to avoid military service. Considered among the most active Holocaust deniers in the world, he was arrested in Canada in February 2003.

Zundel was among the first right-wing extremists to use the Internet to spread hate material. Canada expelled him after courts there found his Web site to be unconstitutional. He was one of several Holocaust deniers deported to Germany at about that time.

He co-wrote the book “The Hitler We Loved and Why” under the pseudonym Christof Friedrich.