SYDNEY, May 26 (Reuters) - Australia mining billionaire Gina Rinehart's two eldest children have won the right to sue their mother for a larger stake of her fortune, ensuring a long-running public dispute over mining profits will continue to play out in court.
Bianca Rinehart and John Hancock are claiming valuable mining assets were wrongly transferred by their mother from a family trust estimated to be worth A$4 billion ($2.88 billion) set up to benefit them by their grandfather, Lang Hancock.
Australian Federal Court Justice Jacqueline Gleeson on Thursday ruled that a dispute over the validity of a number of deeds preventing the Rinehart children suing their mother should go to trial and not to confidential arbitration, as Gina Rinehart had sought.
The two children argue they were pressured into signing the deeds.
Bianca Rinehart and John Hancock launched legal action against their mother in 2011, alleging she acted "deceitfully" and with "gross dishonesty" in her dealings with the trust, set up in 1988 by her father with her children as the beneficiaries.
The case has laid bare the family's testy relationship even as Rinehart's fortunes fall.
An annual BRW Australian rich-list poll by Fairfax Media showed Gina Rinehart dropped to fourth from first, with her wealth falling from A$14.02 billion last year to A$6.06 billion.
The drop in ranking came on the back of a slump in iron ore prices.
Bianca Rinehart ranked 60th, with A$905 million in personal wealth, according to the list. ($1 = 1.3891 Australian dollars)