Justin Bieber has vowed not to act on his love for Beyonce Knowles because he has too much respect for Jay-Z.

The Canadian singer thinks the star is one of the best looking women in show business.

Although he would love to get to know her a little better, the 18-year-old has joked he'd hate to be labelled a home-wrecker.

"Beyonce. She's so sexy. I'm in love with everything about her,'' he told Q magazine, when asked who he would like to follow him on Twitter.

"But I love Jay-Z, so I can't do anything about it. I've had a crush on her for a long time. But I wouldn't come between them - I would never do that!

"But I'm going to make her follow me (on Twitter) just by keeping talking about it.''

Bieber is dating fellow singer Selena Gomez and has spoken about what he looks for in a woman. He is a fan of curvaceous singers, explaining there is another star whose body he admires.

"I think I'm a butt guy. I just like butts. I'm attracted to them,'' he said. "Do I have any favourites? Nicki Minaj has got a nice one."

Bieber is known for having crazy fans who follow him everywhere and he admits finding it strange that some of his younger admirers seem so infatuated with him.

"I don't really agree with 12-year-olds talking about those inappropriate things,'' he said.

"I just think the younger people are, the closer the parents should watch out over the kids. But once they turn 13, it's easier because they're going to learn that stuff anyway.''

- AAP