Antisemitic text implying that Anne Frank's diary was a forgery was projected onto the Anne Frank House in Amsterdam this week, the museum announced in a statement.
"The Anne Frank House organisation has learned of this with shock and revulsion," the museum said.
The projection on the house where the Frank family hid during World War II read, "Ann Frank [sic], inventor of the ballpoint pen."
It alludes to a debunked far-right conspiracy theory that the diary was a forgery because part of it was written in ballpoint pen, which were not yet in use while Anne lived. The theory was meticulously and scientifically disproven by the Dutch government, The New York Times reported in 1989.
This false claim is used to question or deny the Holocaust.
Footage of the projection appeared in a hate video in a private Telegram group from the U.S., the museum's statement says.
Dutch police said they are investigating the incident, according to the Associated Press. The museum says it is in touch with authorities and the Amsterdam City Council.
Dutch Prime Minister Mark Rutte called the projection "reprehensible" and said there's "no place for antisemitism in our country" on Twitter.
Anne was a Jewish girl who kept a diary while in hiding with her family for about two years during World War II. The journal chronicled her life, feelings and thoughts.
She died in a concentration camp in 1945.
Her father, Otto, survived the Holocaust and published her diary, which has since sold more than 30 million copies and been translated into dozens of languages.
"The diary of Anne Frank is one of the most important testimonies of the persecution of the Jews during the Second World War," the museum's statement says.
