Black Eyed Peas star has insisted controversial pop stars like Justin Bieber have any obligation to be a "role model" and thinks they face a tough time growing up in the public eye. doesn't think Justin Bieber has to be a "role model".

The superstar producer has suggested both the 'Beauty and a Beat' singer and Miley Cyrus are under a lot of pressure as they struggle with "growing up" in front of the world, and doesn't blame them for their controversial behaviour.

He told The Sun newspaper's TV Magazine: "Those particular pop stars are just graduating into adulthood.

"Part of the reason that I feel Justin Bieber has had a hard time growing up is because the spotlight and magnifying glass is on him.

"It's really not important that pop stars are role models. There are no rules on how a pop star should act."

The Black Eyed Peas singer has managed to stay grounded because he doesn't want to embarrass his mother with crazy behaviour, and they still have a close relationship.

He said: "I talk to my mom every other day. At the age I am now, my mom already had three kids - all by herself.

"She's most proud of what I choose to use my success for. To aim it in areas that are beneficial to others."