Global mining firm Rio Tinto Ltd said on Wednesday that it is sticking with an earlier deal sealed with the federal government on the minerals resource rent tax, notwithstanding the reservations recently aired by its fellow giant miner BHP Billiton Ltd.

Allegedly questioning the government's intention of honouring the deal, also made with Xstrata, BHP Billiton allegedly warned that vague provisions on the proposed tax's state royalties could push its to renege on the pact.

However, Rio Tinto Australia chief Sam Walsh said that such is not the same with his company and no considerations were even mulled on abandoning the mining deal as he pointed out that the ball is now in the hands of the government to observe and respect every provision of the agreement.

He said that he is under the impression that all parties involved in realising the pact, including the government, were placing much importance on the mining deal and nobody would be making a move that would be of disservice to the deal.

Mr Walsh added that discussions by the Rio Tinto and the government on the mining tax have been continuous and with that as a backdrop, the company is pushing forward its $3 billion expansion programs on its iron ore operations in the Pilbara region of Western Australia.

The expansion covers for the improvement of Rio Tinto's existing port and rail facilities at Cape Lambert, which Mr Walsh said would best serve the company's vision of boosting its iron ore exports from the region to an estimated 280 million tonnes by 2013.

Rio Tinto said that its future outlook for Australia's commodity exports remain positive due to the consistently solid demand coming from China and other countries from Asia as it added that its expansion programs came on the heels of ramped up iron ore productions by its rival, BHP Billiton, during the last quarter.

The Pilbara expansion would also proceed despite the recent scrapping jointly decided with BHP on their $120 billion iron ore operational partnership in Pilbara due to oppositions raised by some regulatory bodies of governments across the globe.