In a submission to a Senate inquiry scrutinising the government's proposed higher education changes, the university argues that claims of soaring fees have been "wildly exaggerated".

Preliminary modelling by the university shows that fees for three-year business and law degrees – which currently cost $32,000 – are likely to remain "considerably less" than $100,000, the submission says.

The University of NSW said fees would need to rise by 24 per cent to compensate for cuts to government funding, but that any increases would not be "excessive". UNSW said it would use most of the income from increased fees to reduce class sizes.

But Bruce Chapman, the architect of the HECS student loans system, said fee deregulation would lead to "price gouging" as universities jacked up fees to fund research and infrastructure investments that would previously have been paid for by government.

Professor Chapman said the government should abandon its "radical" plan to allow universities to set their own fees and said it had rushed into sweeping changes without enough consideration.

It would be fair to increase the current caps on student fees, but full fee deregulation goes too far, Professor Chapman said.

"It is not responsible to allow universities to charge whatever they want," he said.

"Why should students be paying for research and other areas beyond teaching? It is an ethical question."

In a Senate submission, Professor Chapman and Australian National University colleague Timothy Higgins write: "[W]e are very concerned about the apparent haste and seeming lack of expert consideration of the many complex and potentially inequitable outcomes implicit in the suggested radical fee deregulation agenda that makes up the Commonwealth's plans."

The fact students do not have to pay their fees until they are earning a decent wage will dilute price competition, allowing universities to double or even triple their fees for prestigious courses, Professor Chapman said.

A spokesman for Education Minister Christopher Pyne said students already cross-subsidised university research.

"Under the governments changes the HECS-HELP system, a positive legacy left by Professor Chapman, will continue, meaning no student will pay a cent upfront and no one will need to repay the cost of their degree until they are earning over $50,000 a year," the spokesman said.

The University of Western Australia revealed this week that it would charge a flat $48,000 for a three-year degree if fees are deregulated.

The University of Sydney says in its submission that competition between universities and the need to encourage students to study double degrees will keep tuition costs low.

A spokeswoman said the full modelling of fee rises was not available for release.

"We remain of the view that the current funding framework has passed its use by date," the university submission argues. "We do not believe that further tweaking or short-term fixes will be sufficient to underpin in the long term a high-quality Australian higher education."

Labor, the Greens and the Palmer United Party have said they will vote against fee deregulation in the Senate.

Opposition higher education spokesman Kim Carr called on the University of Sydney to release its full modelling.