US President Barack Obama said he was "shocked and saddened" by the recent suicides of several young people who were bullied and taunted for being gay.

"As a parent of two daughters, it breaks my heart. It's something that just shouldn't happen in this country," Obama said in a video posted late last night on YouTube and the White House website.

It is time, he said, for Americans to dispel the myth that bullying is "just a normal rite of passage".

"I don't know what it's like to be picked on for being gay. But I do know what it's like to grow up feeling that sometimes you don't belong," Obama said. "It's tough."

The victims of bullying can sometimes feel that they are responsible for the taunting because they are different or do not fit in with everybody else, he said.

"But what I want to say is this: You are not alone. You didn't do anything wrong. You didn't do anything to deserve being bullied," Obama said.

He encouraged young people who are depressed or down on themselves to reach out to people they trust - parents, teachers, or "folks that you know care about you just the way you are".

"Don't feel like you're in this by yourself," he advised.

Over time, Obama said, "you're going to see that your differences are a source of pride and a source of strength".

Anti-gay bullying has been in the spotlight recently after the suicides of several US teenagers. The victims included Asher Brown, 13, of Houston, who shot himself with his father's handgun, and Tyler Clementi, 18, a New Jersey college student who jumped from a bridge after his roommate secretly recorded him with another male student, then broadcast the video online.