Hackers replaced a Book of the Dead with neo-Nazi slogans and symbols on World War Two concentration camp Buchenwald's website (www.buchenwald.de) on Wednesday and completely erased the Mittelbau Dora camp website.

Brown is beautiful, read one slogan in English, referring to the color of the uniform shirts of Adolf Hitler's SA stormtroopers. We'll be back, threatened another in German.

By damaging the services and documentation that we offer -- such as the Book of the Dead at Buchenwald concentration camp -- the perpetrators were trying to efface the memory of the victims of the crimes of the Nazis, said Volkhard Knigge, head of the Buchenwald memorial foundation, in a statement.

The foundation, which is dedicated to preserving the camp's remains in commemoration of the victims and promoting public knowledge and historical research into the Holocaust, said the hacker attack had been reported to police.

In Buchenwald the Nazis incarcerated nearly a quarter of a million people, many of them Jews, who were forced to work in arms factories. An estimated 56,000 of them died of exhaustion, starvation or illness, or were executed.

Mittelbau Dora nearby also provided forced labor for a Nazi weapons factory and it is estimated that one third of the 60,000 prisoners held there died.

(Reporting by Stephen Brown; Editing by Louise Ireland)