Labor fury over tax-payer funded uni ads

Federal Labor is furious about a tax-payer funded advertising campaign spruiking a planned universities overhaul, claiming the ads aren't even true.

Labor's higher education spokesman Kim Carr is calling on the government to pull the ads, saying they're inaccurate, unnecessary and in breach of guidelines.

"These ads are a disgrace and should be withdrawn immediately," Senator Carr told ABC radio.

The Abbott government launched the campaign after a suite of changes, that among other things deregulate universities, was rejected by the Senate.

A revamped version that includes concessions for crucial crossbench senators was introduced into the parliament before the summer holidays and is due back in the upper house early next year.

The ads claim the government will continue to pay about half the costs of students' degrees.

But Senator Carr says that's incorrect and at several universities the student contribution will be much higher.

Independent senator Nick Xenophon - who holds a key vote on the legislation - says taxpayers should not be footing the bill.

"I've previously complained about the boat ads but at least that was government policy - this law hasn't even passed," he told AAP.

Senator Xenophon has written to the Commonwealth auditor-general to request an investigation of the campaign against the government's guidelines.

Education Minister Christopher Pyne has refused to reveal the cost of the campaign.