Mining giant Rio Tinto has voiced its disappointment over Australia's carbon tax proposal, joining the sector's warning that the plan would hinder investment and jobs growth in the nation's mining industry.In Australia, and the government has decided to implement a tax of A$23 a tonne on the 500 heaviest emitters as of 1 July 2012, as part of a scheme to cut 159m tonnes of carbon pollution from the atmosphere by 2010.Coal accounts for 37% of the Australia's emissions."Rio Tinto believes the Government's carbon tax will undermine Australia's international competitiveness and hurt the nation's export-competing industries," the company said.Rio's managing director David Peever said that the proposed tax is "unfair" on Australian exporters and could leave them at a disadvantage to international competitors."It is crucial that Australia's contribution to the global effort is in proportion to action being taken by overseas trading rivals so as not to disadvantage important trade-exposed industries," he said.Sector peer Xstrata has also slammed the scheme, saying that it is disappointed at the government's "lack of genuine consultation".The minerals industry contributes more than 8% of the country's gross domestic product (GDP)."We have to be careful about imposing policy experiments on the Australian economy. Australia's minerals sector now faces significant additional costs not faced by competitors. This will inevitably reduce potential investment and jobs growth in Australia, without reducing global emissions," Peever added.Mitchell Hooke, the chief executive of the Minerals Council of Australia, said, "the Government-Greens carbon tax package announced today is a very poor investment in our environmental and economic future. It is an exercise in revenue-churn futility, not a credible or effective climate change policy."BC