Justin Bieber apologises for zap sign

Los Angeles - Justin Bieber apologised on Wednesday for angrily hoisting his middle finger at paparazzi who buzzed the squeaky-clean pop star and his girlfriend after his birthday dinner in Los Angeles.

The fracas occurred on Tuesday evening when Bieber and Disney starlet Selena Gomez left an Italian restaurant where they had celebrated his 17th birthday.

A grim Bieber made the spontaneous gesture after he took the wheel of their vehicle and Gomez shielded her face. It was a rare outburst by the pop sensation, who is publicly unflappable and upbeat in the toughest of circumstances.

Bieber apologised via his Twitter page on Wednsday saying: "Had a great bday and at the end of the night we got surrounded by paps and i reacted in a way i know better. im sorry (sic)."

Charity birthday present

He added that life has its "ups and downs" and that he would make mistakes, but he would learn from them and try to do the right thing.

On the positive side, he told his 7.8 million followers that they had raised more than $40 000 for a charity that provides clean water in poor nations. Separately, TV talk show host Ellen DeGeneres said she sold a lock of Bieber's hair at auction for $40 668 with proceeds going to an animal charity.