Justin Bieber is facing a backlash for saying he hoped Anne Frank "would have been a belieber".The 'Boyfriend' singer has caused public outrage for writing a message in a guestbook at the Anne Frank Museum in Amsterdam, suggesting the Holocaust victim would have been among his legions of devoted fans, with users on social networks branding him insensitive and "self-serving".The 19-year-old pop superstar, who visited the attraction last Friday (12.04.13) while in the country for his 'Believe' world tour, wrote: "Truly inspiring to be able to come here. Anne was a great girl. Hopefully she would have been a belieber."The term is used to describe Justin's most diehard fans, who are generally teenage girls.The message was publicised by the museum - which is situated in the house Anne and her family hid from the Nazis during World War II - on its Facebook page, and has sparked anger on social media networks for cheapening her legacy. One commenter on the Facebook page blasted the 'Baby' hitmaker for turning the "inspirational" moment "into something about yourself".Another called the stunt "self-serving" and added: "[He] completely missed the lesson in front of him. Shows his complete LACK of Maturity. (sic)"A spokesperson for the museum defended the singer, however, telling BBC, News: "He's 19. It's a crazy life he's living, he didn't mean bad ... and also it's nice that he made the effort, he didn't have to come."Anne became an important historical figure following her death for detailing the suffering of Jews in Europe during World War II in a diary, which was later published and used as the basis for many films and plays. The teenager and her family went into hiding in a secret compartment of the Amsterdam home in 1942, but were betrayed two years later. The teenager later died in Bergen-Belsen concentration camp at the age of 15, and the house was turned into a museum in her memory.