Pop star Justin Bieber has publicly addressed his use of marijuana for the first time.

The 18-year-old singer used his appearance on Saturday Night Live to apologise to fans for smoking the drug in a hotel room with friends.

Speaking in the third person in a sketch in which he played the president of the Miley Cyrus fan club, he described himself as a "douche" before touching on his pot-smoking habit.

"I also heard he [me] got busted for smoking weed and he's really sorry about it and people make mistakes and he's never gonna do it again, " he said in the sketch.

The teen sensation made headlines when pictures of him smoking marijuana with a friend during a party in Newport Beach surfaced online.

The images sparked accusations that he was setting a bad example for his young fanbase.

Although Bieber did not openly admit doing drugs at the time, he sent a cryptic message to his 32.7 million Twitter followers saying that he was still young and would make mistakes.

"Everyday growing and learning. Trying to be better. U get knocked down, u get up," he wrote.

"I see all of u. I hear all of u. I never want to let any of you down. I love u. and thank u. #beliebers."