Fortescue Metals Group, Australia's fledgling iron ore miner, is a step closer to winning its long-running battle against BHP Billiton after Australia's High Court handed down a unanimous ruling that paves the way for the global mining group's rivals to gain access to its private rail network.

Fortescue, which began its first shipment of iron ore to China this year, argued that a section of a railway line in the Pilbara region of Western Australia operated by BHP should be declared a service and Fortescue should have access to it.