Opposition finance spokesman Andrew Robb said today that the federal government would have to issue an emergency mini-budget if it plans to re-study the proposed mining tax as he scored Treasurer Wayne Swan's claim that reconsidering the tax measure would not impact the national budget.

Analysts are speculating that the resource super profits tax would be re-engineered shortly in the wake of recent pronouncements by both Prime Minister Julia Gillard and Mr Swan that they were opening the table for possible adjustments on the RSPT.

The federal government is eyeing to collect a projected $12 billion in the first two years of the tax's implementation, which in turn would be allocated to fund the superannuation contribution, slash the corporate tax and push for more infrastructure projects across the country.

Mr Swan said that the tax would not affect the government's planned return to surplus by 2013 but Mr Robb refused to buy the federal treasurer's position, claiming that "Wayne Swan is a lightweight when it comes to running this country. He's dangerous in the way in which he is going about this."

He added that Mr Swan's fiscal policy has created uncertainty that endangers the future prospects of the country and the government's "mixed messages being sent around the world are just going to add to the confusion and the sovereign risk that is now occurring."

For his part, Mr Swan denied that a mini-budget would be required for the budget to return to surplus, stressing that "it is in no way dependent upon revenues from the mining tax and is in no way affected by the outcome of the negotiations that we are having with the mining industry."

Attending the on-going G20 meet in Toronto, he admitted though that cuts would have to be made on funds allocated for projects should major adjustments made to the mining tax would reduce the projected revenue, adding that "those initiatives were dependent on the revenue on the mining tax."

The new Labour leadership is expected to fine-tune the proposed tax following the ouster of Kevin Rudd as prime minister last week and analysts are expecting Ms Gillard to accept some compromise over the measures if only to settle the controversies generated by the issue.

Analysts are speculating that the government may be willing to change the 40 percent headline rate of the tax but Mr Robb is discounting the possibility that any substantial changes would be made before election time.

He said that the Labour party would only mislead the country and push for the proposed tax even beyond the election period, then deal with "the substantive decisions of the mining tax and then put this tax in when they get back into government if they do so."