UPDATE 1-Rio Tinto wins ruling to keep others off iron ore railway
* Regulator backs big miners' view on rail access
* Rival Fortescue says disappointed, considers appealing
MELBOURNE Feb 11 (Reuters) - Rio Tinto said on Monday an Australian regulator has ruled that the firm's key iron ore rail lines do not have to be opened to rival miners, reinforcing the world No.2 iron ore miner's grip on the global market.
The fresh ruling by the Australian Competition Tribunal marked the latest defeat for Fortescue Metals Group in a fight it has been waging since 2004 to force Rio Tinto and BHP Billiton to open their rail lines to others.
"This is great news," Rio Tinto's acting iron ore chief Paul Shannon said in a statement on Monday.
Fortescue is considering its position, spokeswoman Yvonne Ball said, although the company has long since built its own multibillion dollar rail line to become the world's no.4 iron ore miner.
The mega miners have long argued that their rail networks are integral parts of highly efficient mine, rail and port operations and allowing other companies' trains on the lines would hurt their businesses.
The tribunal had previously said Fortescue could use Rio's Robe rail line but not its Hamersley line in a ruling on an appeal by Rio against a 2008 decision by Federal Treasurer Wayne Swan ordering Rio to open both those rail lines and requiring BHP to open its Goldsworthy line.
The case went all the way to the High Court, which last year ordered the Australian Competition Tribunal to rule again on Rio Tinto's appeal against Swan's decision.
Fortescue expressed disappointment with the tribunal's move to to dismiss Swan's decision.
"It is regrettable that the Competition Tribunal did not see the merits of providing third party access to this infrastructure to enhance competition," Chief Executive Nev Power said in a statement, adding that Fortescue would let others use its railway.
The tribunal's decision is due to be publicly released later on Monday.