Gina Rinehart loses bid to suppress details of estranged childrens' legal challenge

Mining magnate Gina Rinehart has lost her bid to keep secret details of her two estranged children's latest court challenge.

In the latest legal stoush to embroil the Rinehart family, John Hancock and his sister Bianca have launched Federal Court proceedings against their mother's company Hancock Prospecting.

Ms Rinehart and her company had sought to extend an interim suppression order on the full details of their claim, saying if aired there was a "real risk of commercial harm" to mining projects such as the multi-billion dollar Roy Hill.

The project in Western Australia's Pilbara region is to start exporting in 2015.

But Justice Peter Jacobson rejected her application on Wednesday, saying the substance of the allegations were already in the public domain and there was a public interest in open justice.