Mine tax set to pass Senate

Prime Minister Julia Gillard's mining tax looks set to pass the Senate tonight, after the Australian Greens signalled they would vote for the legislation even though their preferred amendments have been rejected by the government.

Ms Gillard told reporters in Canberra the government was determined to deliver MRRT-funded tax cuts to business.

"We will bring the legislation to parliament exactly as we outlined," she said.

"I think it is a truly remarkable thing that the Liberal Party will sit in the parliament and will vote against a tax cut for Australian businesses."

Ms Gillard challenged Opposition Leader Tony Abbott to use his budget reply speech in May to outline how he would fund his election promises.

She said the government's figures would be outlined in full in the budget papers.

"What you should expect is for the government to take the prudent approach it has to government spending," she said of the upcoming budget.

"It's in the interests of the Australian economy and the Australian people that we return the budget to surplus."

Australian Greens leader Bob Brown says his party would be back the mining tax laws, but said they fall "way short of the mark".

"There some really important amendments to this tax which would make it better for all concerned if the opposition were to join the Greens in supporting those amendments," Senator Brown told reporters in Canberra.

"A primary one is the pretty daft part of this legislation which says that the commonwealth will refund increases in state royalties to the mining companies involved."

Senator Brown said the tax fell "way short of the mark".

"We will be voting for it because the alternative is to raise nothing," he said.

The Greens want the tax on coal and iron ore extended to gold and uranium.

By not expanding its scope, both Labor and the coalition risked putting "black holes" in their budgets, Senator Brown said.

"The federal government says it won't support anything (in the Greens amendments)," he said.

"They are creating their own black holes when it comes to funding disability, education, the need for further public infrastructure like high-speed rail.

"The challenge is (also) to Tony Abbott's opposition - here is your opportunity to reduce your $70 billion black hole."

Senator Brown said the government's decision to back a Greens plan to provide regular updates on mining tax revenues would help all parties to design their budgets and cost their election promises in 2013.

Liberal frontbencher Eric Abetz said the tax would be to the "long-term detriment of the Australian economy".

Nationals senate leader Barnaby Joyce said mining companies were already paying their fair share.

"We have a mining tax - it's called state royalties," he said.