Rio Tinto has denied media reports that it has shelved projects in Australia in response to proposals for new taxes on miners' profits, but said it is 'reviewing the possible impact' of the tax.Prime Minister Kevin Rudd wants to slap a 40% tax (Resource Super Profits Tax) on resource projects from July 2012, which could raise about A$12bn ($11bn) in the first two years.Rio, which has about a third of its assets in Australia, said it is continuing a feasibility study into the proposed expansion of its mining assets. It said it will be 'unable to determine the impact of any RSPT on the ... expansion study until the details of the government's proposal become clearer.'Rio's statement comes after fellow Australia-facing miners BHP and Xstrata voiced their opposition to the proposals.BHP said the new tax would increase the total effective tax rate on the group's profits earned from its Australian operations from around 43% to around 57% from 2013.Xstrata also warned that additional taxation on the industry 'could well curb the large scale, long term investments required to develop Australia's natural resources for the benefit of all Australians'.