Mining giant Rio Tinto Thursday reported a 82 percent drop in its first-half net profit as a supply glut and slowing Chinese demand sent iron ore prices plunging.

The Anglo-Australian firm said net profit was $806 million in the six months to June 30 from $4.4 billion in the same period last year.

Its underlying profit, the measure preferred by the company, was down 43 percent to $2.9 billion.