Heather Mills McCartney is refusing to let step-daughter Stella McCartney see her half sister Beatrice.The former model, who split from Stella's father Sir Paul McCartney in May, is even threatening to apply for a court order to ban Stella from visiting the two-year-old.Heather is reportedly furious after a hearing a taped phone conversation where the fashion designer called her a "liar" and dismissed her charity work.A source told Britain's Sunday Mirror newspaper: "Heather and Stella are at war. It is as simple as that. The pair have disliked each other for years but always put on a brave public face for Paul's sake. Heather does not want Bea to see Stella ever again."In the recorded conversation, Stella told her father she thought Heather had lied about her past and believes the claims her step-mother was once a high-class prostitute.She is also said to have launched a bitter attack on Heather's anti-landmine campaigning and anti-fur protests.Paul reportedly went "white as a sheet" when Heather played the explosive tape to him two weeks ago.

He is said to be devastated by the thought of never being able to see his two daughters at the same time.

Stella has been a constant source of comfort to her father since his split from Heather and he loves spending time with her.

A source said: "He adores Stella and has been relying on her. Bea is his baby girl and she means the world to him."

Stella and Beatrice last saw each other at Paul's 64th birthday party last month.