Fortescue and the state of Western Australia have been hit with a $1.8 billion native title claim in an extraordinary escalation of a long-running battle over the Yindjibarndi lands on which the company built its Solomon iron ore mining hub.

The miner is expected to report a $2.6 billion half-year profit on Thursday, but now must factor in the risk of a dramatically higher than expected claim by the Yindjibarndi people.