Rio released a statement on Monday saying that the Australian Competition Tribunal had ruled that it did not have to open Rio's 1,400km of rail lines in Western Australia's Pilbara to other miners wanting to transport iron ore.
Fortescue chief executive Nev Power said it was regrettable that the tribunal did not see the merits of providing third-party access to enhance competition and deliver greater productivity and efficiency benefits.
The business community has been calling for more government investment in infrastructure to tackle export bottlenecks that affect productivity and costs.
"Rio Tinto runs a highly efficient railway that is fully integrated with our port and mine operations," he said in a statement.
While Fortescue ultimately built its own multi-billion-dollar rail line, it became saddled with debt doing so.
The tribunal decision does not affect Fortescue's current operations and expansion plans, it said.
The prohibitive costs of building infrastructure prevents smaller iron ore explorers from becoming successful producers and reinforces the dominance of BHP and Rio, which along with Brazil's Vale control three-quarters of the two billion tonne a year global iron ore industry.