Australian miner Fortescue Metals on Monday posted an 88 percent slump in full-year net profit on the back of tumbling prices for the steel-making commodity iron ore.

Fortescue, one of the world's big four iron ore exporters along with Australia's BHP Billiton and Rio Tinto, and Brazil's Vale, made a profit of $316 million for the 12 months to June 30, down from $2.74 billion a year earlier.

The result missed analyst expectations, sending the embattled company's shares nearly eight percent lower to Aus$1.76 in morning trade.

The miner has been battling a supply glut and softening Chinese demand, which has seen the ore price plunge, hitting its lowest level since 2009 last month at $44.59.

Chief Executive Nev Power admitted it had been "a challenging environment" with fellow giant Rio Tinto posting an 82 percent slump in its first-half net profit earlier this month, with softer commodity prices also weighing heavily.

BHP reports its annual results on Tuesday.

"In a challenging environment of lower iron ore prices, the focus on efficiency and productivity from our world class assets will continue to see operational improvements and cost reductions," Power said.

He added that the company aimed to maintain shipments of iron ore at 165 million tonnes annually "to create long term value for Fortescue shareholders" despite an increasingly oversupplied market, which has forced the ore price down.