Finance and Deregulation Minister Penny Wong has left the door open to the establishment of a sovereign wealth fund (SWF), but ruled out using the revenue from the minerals resource rent tax (MRRT) for such a fund.

"The issue of a sovereign wealth fund is not an uncommon topic of discussion," Wong said at the Economist Conference Bellwether series in Sydney on Tuesday.

"Obviously in terms of the MRRT, we have already indicated what that money would be spent on, which is a reduction of the company tax rate with a headstart for small business . and the superannuation, which is obviously an investment for the longer term.

"In terms of where future surpluses will go, as the Treasurer has said that is obviously a policy question that the government is open to."

Federal Treasurer Wayne Swan earlier that day said the expected revenue stream from a mineral tax would not be enough to justify the establishment of an SWF.

"It wouldn't do anything in our current situation and it wouldn't do anything for some time to come," Swan said in an interview with ABC Radio.

"Commonwealth revenues are down $130 billion to what they were prior to the onset of the global financial crisis and the global recession. It is going to take some time for those revenues to return.

"There will be some substantial revenues flowing to our country over time, but not significant enough to build up the sort of sovereign wealth fund that those people are talking about."

He also rejected the idea of restructuring the $75 billion Future Fund so it could function as an SWF.

"The future fund is there for, and dedicated to, the public service superannuation liabilities and it is dedicated against that liability for the future," he said.

The MRRT legislation is scheduled to go to Parliament later this year.