Billionaire Andrew Forrest has addressed staff after disturbing allegations of sexual harassment at Fortescue mine camps were disclosed in a class action against the miner.

Andrew "Twiggy" Forrest's mining giant Fortescue has been slapped with a landmark class action alleging systemic sexual harassment, discrimination and toxic work sites.

Fortescue Metals Group has been sued by female workers who allege there is widespread sexual harassment and assault at the company’s remote sites.