Justin Bieber and Selena Gomez have broken up for good.

The 'Baby' singer had a huge bust up with his girlfriend on the day before New Year's Eve (30.12.12), prompting her to fly home to the US from the resort of Puerta Vallarta in Mexico.

Multiple sources have since confirmed to Us Weekly the on/off couple have now split for good.

A source said: ''He's been really down about the break-up.''

Selena spent New Year at a house party with her friends, while Justin partied at Los Angeles club Couture with rapper Lil' Twist.

The 18-year-old star has since been pictured smoking marijuana, with some blaming Justin's rapper friend as a bad influence.

The incident was the final nail in the coffin of the romance for Selena who was unimpressed by his actions.

Another source added: ''Selena is done with him.''

The 'Monte Carlo' actress tweeted on January 2: ''New beginnings. Fresh start. I love you all :) (sic)''

Justin appears to have taken the split harder, and was reported to be desperately calling his ex since she called time on their relationship.

Another source said: ''Justin's devastated and pathetic right now. He's calling her 100 times a day and she's not picking up.''