Australian federal treasurer Wayne Swan has been urged to change the mining tax after it raised well below the amount of money forecast.
Mr Swan on Friday said the tax raised $A126 million in its first six months, well short of the $A2 billion that Treasury had predicted for the year.
Mr Swan cited a huge drop in commodity prices and a higher Australian dollar for the shortfall.
The Greens are planning to move a bill in Parliament next week to fix some of the loopholes.
They argue state royalty increases should not be refunded by the Commonwealth, that the tax rate should be increased to 40% and that the tax should be broadened to include other minerals.
Federal independent MP Rob Oakeshott said he hopes Mr Swan will show some courage and take the lead.
The Minerals Council said any changes to the MRRT will be resisted.
Director Ben Mitchell said the tax was negotiated extensively with the industry and should not be changed.
"There would have to be extensive negotiations with industry ... but I don't think the Government is going to be in a mind to do that.'' he said.
Mr Mitchell said the tax was designed to raise revenue only when profits are high and it was operating as it should.
Prime Minister Julia Gillard renegotiated the mining tax with BHP Billiton, Rio Tinto and Xstrata soon after she took over from Kevin Rudd as prime minister in 2010.
