The Canadian teenage pop sensation Justin Bieber, who shocked many by hoisting the middle finger at the paparazzi on his 17th birthday in Los Angeles, has apologized for his act on Twitter. Although this is the first time Bieber was caught in the 'act of rage', there have been several small instances of the singer flipping off in the past. And the evidence lurks on the internet.

In a rare outburst from a pop star known for his mild manners and flip of his lustrous hair, Bieber on Tuesday flashed a middle finger at paparazzi who swarmed him and his girlfriend, Selena Gomez, after his birthday dinner in Los Angeles.

The incident took place when Bieber and Gomez stepped into the car after leaving an Italian restaurant where they had celebrated his 17th birthday.

Bieber, however, was quick to apologise. He tweeted on Wednesday: Had a great b'day and at the end of the night we got surrounded by paps and I reacted in a way I know better. I'm sorry.

It's not always easy but I know better than to react in anger.

This is, in deed, the first instance of Beiber reacting in anger. Nevertheless, there have been few other seemingly unconscious and innocent incidents of the teenage heartthrob showing the middle finger.

In a YouTube video posted by a Bieber fan, the teenager is seen flashing the finger in the middle of a performance.

And no i don't think it was on purpose, the fan writes in the description of the video uploaded in July 2009.

Another image on shows Bieber hoisting the middle finger. The year old picture had created same waves when it first hit the internet but the heat soon died down.