Justin Bieber has caused outrage after suggesting Anne Frank would have been a ''belieber''.

The 19-year-old pop star has been faced with a torrent of angry messages on social networking sites after it emerged he had left a comment in the Anne Frank guestbook during a recent visit to the Holocaust victim's house in Amsterdam, which is now a museum.

Justin wrote in the guestbook last Friday (12.04.13): ''Truly inspiring to be able to come here. Anne was a great girl. Hopefully she would have been a belieber.''

The Anne Frank House appeared to be truly touched by Bieber's comment, writing on Facebook: ''Yesterday night Justin Bieber visited the Anne Frank House, together with his friends and guards.

''Fans were waiting outside to see a glimpse of him. He stayed more than an hour in the museum.''

The teenage heartthrob used his spare time ahead of his Believe tour gig in the Netherlands to visit the museum, which was originally the hiding place of Anne and her family from the Nazis during World War II.

While Justin was branded ''self-serving'' and insensitive online, a spokesperson from the museum was quick to come to his defence.

They said: ''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.''