Gina Rinehart’s Hancock Prospecting has warned that iron ore demand has “plateaued” as the mining group owned by Australia’s richest person diversifies with investments in lithium and rare earths.

Hancock on Friday said its net profit fell 44 per cent to A$3.1bn (US$2bn) in the year to June as the iron ore price declined and severe storms disrupted shipments from the Pilbara region of Western Australia. Revenue fell 21 per cent to A$11.6bn.

Iron ore is Australia’s largest export, accounting for as much as 4 per cent of the country’s GDP, according to economists. But weakening demand from the Chinese property sector and the official launch later this year of the Simandou mine in Guinea, part-owned by Hancock’s partner Rio Tinto, has put pressure on prices.