Los Angeles - Justin Bieber was bullied as a child.
The 18-year-old heartthrob - who has leant his single Born to Be Somebody
to a US documentary on school bullying - admits he fell victim to tormentors before becoming famous.
He said: "I was bullied. Most people in their lifetime have been bullied at some point. I think that it's about time that people start making a change."
The film, titled Bully
looks at the issue through the eyes of five youngsters, and the Boyfriend
hitmaker believes it has the potential to make a real difference.'Teachers let it go'
He told Showbiz Tonight
: "A lot of the time, principals let it go, or teachers let it go, or other students just let it go, but I think this movie's really powerful and can help change a lot of lives."
Meanwhile, he urges those who witness bullying, as well as those who experience it first-hand, to share the problem with someone and seek help.
He said: "If you're a bystander, too, tell somebody - because a lot of times, it's just not spoken of, and you ended up - you end up keeping it all inside, and then it just hurts even more."