Australian mining shares fell on Monday amid concerns over a planned tax on mining companies.
On Sunday, the Australian government proposed a new 40% tax on the profits of major resources companies, as part of a wider review of its tax policy.
The world's biggest miner BHP Billiton saw its shares fall 3% on Monday, while rival Rio Tinto was down 4.2%.
Miners have complained that the tax, planned for 2012, would push investment in mining abroad.
BHP and Rio Tinto are expected to be the hardest hit by any tax, as they have the most profitable mining operations.
Rio Tinto reported pre-tax profits of US$7.86bn (£5.02bn) for 2009, while BHP Billiton made profits of US$6.14bn for the last six months of the year.
Mr Rudd said the multi-national nature of the companies meant that a large proportion of the profits were not subject to Australian tax.
BHP is 60% Australian-owned while Rio Tinto is less than 30% Australian.
But the miners themselves have protested, arguing that the success of the sector has helped
Taxing the industry, they argue, will risk harming the economy.
"These proposals seriously threaten
Mining has seen a boom in recent years - particularly in iron ore mined in
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