Singer Justin Bieber attends a ceremony where Michael Jackson's shoes and gloves are used to make hand and foot imprints in cement in the courtyard of Hollywood's Grauman's Chinese Theatre in Los Angeles on January 26, 2012. [Photo/Agencies]

Justin Bieber is threatening game developers with legal action for using his image for a mobile app.

The 'Baby' singer's lawyers have issued a cease and desist letter to company RC3 over their cartoon game 'Joustin' Beaver', according to website TMZ.

In the game, the player has to get a beaver - who bears a resemblance to the pop singer - to sign 'Otter-graphs', while defending him from 'Phot-hogs' as they float downstream.

Justin's representatives are demanding the $0.99 game be removed from sale on iTunes and asking RC3 to hand over their accounting and revenue figures.

However, the company is defending itself, saying the game is a parody and therefore protected by the US First Amendment.

Justin - who turns 18 next week - recently admitted now he is a huge megastar he has become a target for people, but he does his best not to let it get to him.

He said: ''Now that I'm on top, everyone wants to bring me down. Everyone's trying to tug at me and take my spot.''

He has also said his faith in God helps him to keep strong.

Justin - who has a tattoo of Jesus Christ's face on his left calf - said: ''A lot of people who are religious, I think they get lost. They go to church just to go to church... but for me, I focus more on praying and talking to Him. I don't have to go to church.''