Swift: 'Jonas cheated on me with Belle'

Country music star Taylor Swift has accused Joe Jonas of dating actress Camilla Belle behind her back.

Jonas reportedly dumped Swift over the phone earlier this year and has since been linked to 10,000 BC star Belle.

Speaking at last night's Country Music Awards, Swift claimed that the relationship between Jonas and Belle was the catalyst for their split.

"They've been together for months. That's why we broke up," she told OK!

The 18-year-old was nominated for the Female Vocalist Of The Year prize at the ceremony, but lost out to 2005 American Idol winner Carrie Underwood.