Gina Rinehart’s son John Hancock told his sister Bianca she was “weak” and would “sidle up” to their mother in a bitter dispute over a family trust, in a personal email exchange aired for the first time in a separate fight over mining royalties.

Scores of emails between Mr Hancock and his sister Bianca Rinehart in the mid-2000s were divulged in the West Australian Supreme Court on Thursday in the trial to decide a multipronged dispute over revenue worth billions of dollars.