AUSTRALIA'S richest woman is fighting to block anyone knowing why her youngest daughter has taken her to court.

The media was today banned from seeing court documents after lawyers for mining magnate Gina Reinhart asked for 24 hours to file material explaining why the case should be kept permanently under wraps.



The matter, listed in the NSW Supreme Court as Hope Reinhart Welker v Gina Reinhart, was listed before Justice Paul Brereton for a directions mention earlier today.



However, a barrister for Ms Reinhart requested the file be kept confidential, with access only to the parties and their legal representatives.



He argued any publication of the details of the case may "impact on commercial negotiations".



Justice Brereton said the media would, ordinarily, be entitled to inspect certain parts of the file.



Nonetheless, he imposed a 24-hour blackout to enable Ms Reinhart's legal representatives to prepare to argue for a full-time suppression order at 3pm tomorrow.



Neither Ms Reinhart or her daughter was in court today.



Ms Reinhart, the only daughter of mining magnate Lang Hancock, inherited her father's wealth and in May was announced as the first woman to top the BRW Rich List, with a $10.3 billion fortune . She was named as Australia's richest person, after her assets more than doubled in the previous 12 months.



She has four children, and Mrs Welker is a twin who recently married mining executive Ryan Welker.