pbr Avid Justin Bieber fans, known as Beliebers, have threatened to kill Selena Gomez after pictures emerged of the singers kissing on a yacht.br ppbr The teen stars were holidaying with friends in St Lucia over the New Year weekend.br ppbr However, Bieber fans were quick to criticise the union posting hundreds of messages threatening violence towards Gomez on Twitter.br ppbr One message read, "Roses are red, violets are blue, @selenagomez if you'll break @justinbieber's heart I'm gonna kill you."br ppbr Other messages for the actress included, ''I'll kill you I swear on GOD!!!'br ppbr The youngsters, who are often spotted together, have previously denied that they are in a relationship with Gomez labelling Bieber a 'brother' figure.