Simon Cowell has vowed to help N-Dubz crack the US.

The music mogul spent time with hip-hop star Dappy - real name Dino Contostavlos - in Barbados over Christmas and the New Year and has offered to help the 'I Need You' hitmakers become a success overseas.

A source told The Sun newspaper: "Dappy has been partying with Simon, who has been turning on the charm with him. N-Dubz have their sights set on America and Simon has made it clear that he could make it happen for them over there."

However, Dappy has reportedly left their manager Jonathan Shalit reeling at the thought he and his bandmates Tulisa and Fazer might be tempted to leave him and join Simon's record label Syco.

Shalit has been further angered by the fact he financed the 22-year-old singer's lavish trip abroad with his girlfriend.

The source added: "Shalit is livid. He paid for Dappy and his girlfriend Kaye to go away for Christmas and New Year. He didn't expect his golden goose to be tempted elsewhere."