Miley Cyrus' representatives have insisted comments she made about smoking marijuana have been "taken out of context".

The singer celebrated her 19th birthday last week with a party organised by her friend Kelly Osbourne.

Over the weekend a video taken at the bash was made public. In the footage, Miley is seen making a joke about her birthday cake which was emblazoned with the face of reggae star Bob Marley.

"You know you're a stoner when your friends make you a Bob Marley cake you know you smoke way too much f**kin' weed," she is heard saying.

The teenager's spokesperson has now slammed reports about the incident, insisting Miley was only joking.

"The cake was a joke and Miley was being sarcastic," the representative told Access Hollywood. "It is being completely taken out of context."

Kelly has also jumped to the defence of the young star.

In 2010, a different video of Miley hit the internet. She was seen smoking a bong, which she later insisted contained the legal hallucinogen salvia. Kelly insists the cake was just a silly reference to that incident.

"Let me make something very clear after Miley Cyrus' salvia incident we started calling her bob miley as a JOKE!" she wrote on Twitter.

"The cake was also A JOKE! It makes me sick that Miley Cyrus' so called friends' would sell her out and lead people 2 believe she is someone that she is not!

"U guys if Miley Cyrus is not recording/filming/touring she is works everyday how could she possible do all that if she was a stoner! #think (sic)."