Dutch police said on Friday they were investigating the projection of an antisemitic laser message onto the Anne Frank House in Amsterdam - an incident the prime minister condemned as "reprehensible"."
The message referenced a far-right conspiracy theory that the teenage Holocaust victim was not the author of her famous diary, and images of the projection were shown on a private U.S. Telegram channel.
"It happened this week. We were notified and we are investigating it," an Amsterdam police spokesman said, declining to give further details.
The Anne Frank House Museum, which preserves the canalside house where the Jewish Frank family hid from the Nazis during World War II, expressed its "shock and revulsion".
The museum, which receives around a million visitors a year, said it had "reported the incident to the police" and was in contact with the city council and public prosecutors.
It said the projected message read "Ann Frank, inventor of the ballpoint pen" - referring to false claims that the diary was partly written with a type of pen that only came into use after the war.
"With the projection and the (online) video, the perpetrators are attacking the authenticity of Anne Frank's diary and inciting hatred. It is an antisemitic and racist film," the museum said.
The museum said it found out the message had been projected onto its exterior for several minutes on Monday evening after the footage appeared in a "hate video" on Telegram.
An antisemitic song plays in the background of the video, said Dutch newspaper Het Parool, which first reported the incident.
The claim is based on the discovery of several sheets in ballpoint found among Anne Frank's papers in the 1980s, but which were in fact left there accidentally by a researcher in the 1960s, Dutch media said.
'Reprehensible'
Prime Minister Mark Rutte condemned the "reprehensible" act. "There is no place for anti-Semitism in our country; we can never and should never accept this," Rutte tweeted.
The incident showed the need for laws criminalizing Holocaust denial in the Netherlands, Justice Minister Dilan Yesilgoz-Zegerius added.
Amsterdam Mayor Femke Halsema condemned the incident as "pure antisemitism".
Anne Frank and her family hid for two years in a secret annex to the canalside house after the Nazi occupation of the Netherlands during World War II, but were captured in a raid in 1944. The teenager and her sister died in the Bergen-Belsen concentration camp in 1945. Her diary, found by her father Otto, became one of the most haunting accounts of the Holocaust, selling some 30 million copies.
But the Netherlands is still coming to terms with its role in the wartime persecution of Jews. There are now concerns about a resurgence of far-right and antisemitic viewpoints.
A recent survey revealed that nearly a quarter of Dutch adults under 40 believed the Holocaust was a myth or that the number of deaths was exaggerated.
In January, Dutch police said they were investigating the projection of racist slogans on Rotterdam's Erasmus Bridge during New Year's festivities.