MELBOURNE, Nov 12 (Reuters) - Australia's Fortescue Metals Group pressured a state government body to fast track its application to damage two ancient rock shelters as part of an iron ore mine expansion in Western Australia, documents showed on Thursday.

The Wintawari Guruma, on whose ancestral lands Fortescue operates, said that the miner had threatened legal action against a government panel tasked with protecting Aboriginal heritage, rather than talk to them about site preservation, in a submission to a parliamentary inquiry.

Fortescue said in a statement that its primary objective was to avoid heritage sites, and that had saved nearly 6,000 sites.

Fortescue Chief Executive Officer Elizabeth Gaines said that the miner had committed to protect and avoid the two rock shelters and that it disagreed with Wintawari's characterisation of its behavior and approach to Aboriginal heritage.

The inquiry is investigating peer Rio Tinto's legal destruction of two historically significant rock shelters in the same region, which took place just weeks after Fortescue's application. Both sets of rock shelters contained some of humankind's oldest evidence of civilisation, showing human habitation stretching back 46,000 years or longer.

The destruction in May, which caused deep distress to the traditional owners, has shone a light on the lack of legal protection for Aboriginal sites, ultimately cost Rio's chief executive his job and forced miners to review their practices.

Fortescue lawyers Green Legal had written to the Aboriginal Cultural Materials Committee in April as part of an application to get approvals for Fortescue's Solomon hub expansion.

The letter, dated April 22, said that if the committee did not make a recommendation to the government about its application by May 19 then it would "compel the ACMC to do so including taking legal action against it."

The Wintawari Guruma said in a separate submission that it considered Fortescue's historical approach to gaining approvals "to be bullying, dismissive, disrespectful, and inconsistent with their published values and the expected behaviors of an ASX Top Ten Company."

The Wintawari told the inquiry last month that Fortescue had withheld royalty payments amounting to A$1.9 million ($1.38 million) because it had declined to sign mining approvals without more information about the miner's plans.

($1 = 1.3789 Australian dollars) (Reporting by Melanie Burton; Editing by Jacqueline Wong)