Justin Bieber left a personal message in the Anne Frank House guest book during his visit in Amsterdam Saturday, Fox News said.
In his message in the museum's guest book, Bieber wrote, "Hopefully she would have been a belieber," the Chicago Tribune said. "Belieber" is the popular term for Justin Bieber fans.
The museum is dedicated to preserving the memory of Frank, whose diary chronicled the teenager's life as she and her family hid from the Nazis during World War II, Fox News said.
The museum's Facebook page has Beiber's full entry as: "Truly inspiring to be able to come here. Anne was a great girl. Hopefully she would have been a belieber." A BBC correspondent confirmed that Bieber's visit and note were authentic, Fox News said.
Many people have voiced their outrage regarding the teen pop star's comment, the Chicago Tribune reported.
"Anne Frank a belieber? That is by far one of the most self-serving things I've ever read, like ever," Facebook user Tania Saez Pinto wrote.
Bieber, 19, has upcoming concert dates in Norway and Denmark for the European leg of his Believe tour.