PERTH (Dow Jones)--Rio Tinto Ltd. (RTP) Iron Ore Chief Executive Sam Walsh said Tuesday that the company has recommenced studies on its multibillion dollar iron ore expansion in Western Australia after the recent mining tax deal with the Australian government. "We're in the process of re-opening studies in relation to our Pilbara expansions," Walsh told reporters on the sidelines of a function. "With the certainty that we've now got with the Minerals Resource Rent Tax, we are now reconfiguring those numbers and the impact back into our projects," he said. In May, Rio Tinto put its Australian projects on hold due to uncertainty relating to the proposed Resource Super Profits Tax. The company wants to increase iron ore production to around 330 million tons a year from around 230 million tons a year by the middle of the decade. Despite the greater certainty generated by last week's tax compromise, Walsh declined to put a timeframe on when Rio Tinto will approve the expansion, which may cost more than US$10 billion. Earlier, Walsh said at a breakfast function that Rio Tinto is continuing to work with regulators in Europe, Japan, China and Australia over the company's proposed iron ore production joint venture with BHP Billiton Ltd. (BHP). There is no timeframe on the regulatory discussions, and the drawn out nature of the process has prevented Rio Tinto and BHP Billiton from doing much of the implementation planning required for the joint venture, he said. -By Stephen Bell, contributing to Dow Jones Newswires; 61-8-9244-4243; [email protected] (END) Dow Jones Newswires July 05, 2010 21:52 ET (01:52 GMT)