Justin Bieber was horrified to find himself in a nightclub "full of old people...over 30".

The Canadian singer is known for being a Bible-reading good guy but admitted to visiting some of London's bars and clubs recently. However, the 18-year-old was quick to point out he didn't indulge in any beverages.

"I went to this spot yesterday, but it was full of old people I can't remember what it was called. I think it was a club," he told Q Magazine. "I mean, the people were, like, over 30.

"I'd like to go to a pub Not that I drink yet.

The pop star is currently promoting his latest album Believe, which shot to number one on album charts across the globe. Yet even with all the success, fortune and adoring fans, Justin admits it can be difficult to look happy all the time.

"You've always got to keep your composure, especially when you're in the spotlight. You have to always have a smile on your face," he revealed.

"I think everybody wants to scream sometimes, just let it all out. Scream in the pillow."