Justin Bieber apologises for racist joke on Twitter: Statement in full

Singer says 'I was a kid then and I am a man now'

Justin Bieber could still be collaborating with Michael Jackson, LA Reid confirms (AP)

Justin Bieber has issued a lengthy apology on Twitter after a video surfaced of him as a teenager making a racist joke that uses the n-word.

The 20-year-old said he had "learned from [his] mistakes" and was quick to point out that the video was made five years ago when he was "reckless and immature".

Published by The Sun, it shows the Canadian singer hanging out with friends as he asks: "Why are black people afraid of chainsaws?"

Guessing the punchline, someone off camera says: "Don't even say it. Don't say it."

But Bieber continues, in full knowledge that there is a camera filming him: "Run n****r, n****r, n****r, n****r, n****r."

The video was apparently filmed as part of a documentary, Never Say Never, leading up to a concert in New York in August 2010, but unsurprisingly didn't make the cut.

It is the latest in a string of high-profile controversies that include photos of Bieber smoking what looked like cannabis, lunging at a photographer, arriving hours late for shows, drunk drag racing in Miami, spitting on a crowd and failing to look after a pet monkey.

Bieber's apology has so far attracted more than 60,000 retweets.