London: Pippa Middleton, Duchess Catherine's younger sister, is not dating ex-boyfriend George Percy, heir to the Duke of Northumberland, says a source.

Middleton and Percy dated in their final year at the Edinburgh University in 2008."They have always just been friends. I don't know how this particular rumour got so out of control. Both of them say they are friends and I've not heard or seen anything to suggest otherwise. I couldn't imagine them together. Their friendship is more like brother and sister," a website quoted the source as saying.