File photo of Canadian singer Justin Bieber during a concert at Palau Sant Jordi stadium in Barcelona
Canadian singer Justin Bieber performs during a concert at Palau Sant Jordi stadium in Barcelona in this March 16, 2013 file photo. Bieber has been accused of attempted robbery, a Los Angeles Police Department official said on May 13, 2014, following media reports that he had tried to snatch a young woman's mobile telephone. REUTERS/Albert Gea/Files

Justin Bieber, the troubled pop singer, is under fire once again after a leaked footage had showed him telling a racist joke.

Bieber is heard telling the N-word in the video which is exclusively obtained by The Sun. The 20-year-old singer is seen greening while telling the racist joke. "Why are black people afraid of chainsaws?" he asks his friends. He answers it himself that they are "afraid of chainsaws" because it says: "Run N*gg*r N*gg*r N*gg*r N*gg*r N*gg*r N*gg*r." Bieber continues to say "Run N*gg*r N*gg*r N*gg*r N*gg*r N*gg*r N*gg*r" multiple times and keeps laughing about it. The video has apparently been around for some time but Bieber and his camp never seem to have shown interest to keep it undercover, Daily Mail reported.

"This video is Justin Bieber and his camp's worst nightmare. Even after the year he's had - when he's never been far from controversy, this tops the lot. Justin has been taken under his wing by some of the best in the industry and they won't stand by him after this. This will be a real kick in the teeth - showing his true colours on film," The Sun quoted one of its sources.

Interestingly, Bieber has been associated with African-American connections throughout his career. He has worked with black artists like Big Sean, Lil Wayne and will.i.am. He has also signed to Usher Raymonfs label RBMG Records. He mentioned in 2013 that he considered Will Smith to be his mentor. He said that he was in contact with Will as they had weekly conversations over the phone. He also said that his "mentor" gave him counselling and discussed "potential" emotional issues with him.

It may, however, be difficult to judge Bieber on the basis of a light moment among friends. Bieber hit it back earlier at his critics who "judged" him for his selection of friends. "It's not your place to judge, God put these people in my life for a reason, and just because they are African-American that makes them bad people? 'These are people that I love and all of us are going to help make the world a better place," he said in favour of a no-racist culture.

Update: Bieber has apologised for the "racist" joke. He said that, five years ago, he had not realised certain words could hurt.

Contact the writer: s.mukhopadhyay@IBTimes.com.au