Australia's top mining resources firms Rio Tinto and Woodside Petroleum have criticised plans to put a fixed price on carbon emission, without a clear form of compensation or exemption for local businesses and industries.

In separate statements issued today, Rio Tinto has sought government policy protection, while Woodside sought exemption for producers and exporters alike.

These reactions came after the Australian Parliament led by Prime Minister Julia Gillard had announced plans to forge ahead in its plan to put a price on carbon amidst environment concerns beginning July 2012. Ms Gillard and other authorities are targeting a fixed price on carbon emissions to finally launch an environmental campaign delayed for the last two years.

Australia's third largest mining company in terms of assets, Rio Tinto said the Australian parliament must offer some compensation and protection under the carbon scheme while Woodside Petroleum, the nation's largest oil and gas producer, said "it should be outright exempt due to its production profile."

Rio said the plan, if not revised would put Australia's industries behind international peers as it would be more costly for domestic firms. A 2009 proposal indicated a $50 billion in compensation to industry and mining over the first decade. Nevertheless, in the 2011 proposal the compensation had not been finalised.

In a letter printed on the Australian newspaper today, Rio Tinto's managing director David Peever said: "Businesses unable to pass a carbon price through to customers, which is most businesses competing in international markets, would simply have to absorb it.

"Depending on the magnitude of the carbon price, this may be manageable when market conditions are favourable and margins are healthy. But when the cycle turns down, it will inevitably be disastrous," he added.

Rio has estimated the company's annual carbon tax bill would be about $154 million if the tax was set at $20 a tonne for every tonne of carbon pollution.

Woodside Petroleum, meanwhile, said in a statement, it should be exempt from paying any carbon tax at all, as a trade-exposed exporter.

"Woodside believes the company's trade-exposed exports should be exempt from any price on carbon, given the absence of an international agreement on pricing greenhouse gas emissions," it said.

"The company accepts the government's intention to put a price on emissions associated with products consumed domestically such as natural gas, but recognises this will lead to an increase in costs for consumers."

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