PM won't rule out super housing deposits

Malcolm Turnbull is refusing to rule out allowing first-time home buyers to dip into their superannuation to help pay for a deposit, saying he won't discuss issues under consideration for the budget.

Liberal backbencher John Alexander insists the government is looking to let people raid their super to buy a home, despite previous denials by ministers.

And while the prime minister has previously labelled the concept a "thoroughly bad idea", he is no longer using such language.

"I'm not going to go into speculation about what is or will not be or is being considered in the budget," he told Sydney's 2GB Radio on Thursday.

"I'm not going to confirm - or I'm not going to discuss - particular issues that are in consideration for the budget."

But Mr Turnbull said the critical issue to tackling housing affordability was boosting supply.

Mr Alexander also said the government was working on changes to negative gearing, which may be presented at the next election.

"But I think the time is of the essence and I think we need to act sooner rather than later," he told Sky News on Thursday.

"We are discussing these policies, we haven't discussed the timing of them."

Mr Alexander chaired a parliamentary committee into housing affordability.

The government has made tackling housing affordability the centrepiece of this year's budget, however it has opposed Labor's plan to limit negative gearing to new properties.

Shadow treasurer Chris Bowen said the government's latest "thought bubble" on accessing super for housing is "dangerous".

He said it would undermine retirement incomes and encourage first home buyers to use their super to bid against investors with continued access to the most generous property tax concessions in the world.

"That isn't a plan, it's a sham and would just increase house prices," Mr Bowen said in a statement.