Fortescue Metals Group has won approval to increase its iron ore exports by 20 per cent, boosting the company's plan to get more iron ore into the market before rivals in Brazil and Africa can bring on more supply.

Fortescue will be able to export 210 million tonnes through Port Hedland before 2025 after the Western Australian government approved an increase from the company's official regulated capacity of 175 million tonnes in a calendar year.