Fortescue Metals Group says it is seeking legal advice in response to the economic watchdog's ruling on access costs to use its railway in the Pilbara.

FMG submitted proposed floor and ceiling costs for third party access to the Economic Regulation Authority in May after Brockman Resources applied to use the railway.

Fortescue has consistently resisted the proposal saying it would restrict all other parties from using the railway.

The ERA has handed down its ruling saying it does not support all aspects of the proposal and has made some recommendations.

FMG has released a statement saying the ERA determination does not trigger negotiations for access with Brockman.

It says Brockman it yet to meet all requirements of the code required for negotiations to start.