Miley Cyrus performs at the Barclays Centre in New York.

London - Miley Cyrus has appealed for Justin Bieber to be allowed to "grow up".

The 21-year-old singer thinks much of the criticism levelled at the 'Believe' hitmaker - who recently apologised after video footage of him making racist remarks when he was 14 was published online - is unfair as most people get to make their youthful mistakes in private.

Speaking on Australia's 'Today' show, she said: "I think people should have time to grow up and figure out who they are.

"I think people need to sit and think of the times in their lives they were not proud of who they were.

"Imagine if that was completely exploited and everyone had their opinions."

However, the 'Wrecking Ball' hitmaker thinks social media is a "blessing" as it allows everyone an outlet for their views.

She said: "Social media is such a blessing. Everyone is allowed have an opinion."

Meanwhile, Miley also revealed a lighting technician was forced to stand in for one of the DJs on her 'Bangerz' tour recently.

She explained: "One of the lighting guys just went out there and DJed. He pretended to have two security guards which were just two other lighting guys dressed in suits." - BANG Showbiz