Former prime minister Tony Abbott says there is nothing "sacrosanct" about Australia's immigration numbers and the government should reduce the migration program to ease housing pressures.

As the government forms its housing affordability package ahead of the May budget, Mr Abbott also endorsed a proposal that would allow people to access their retirement savings to pay for a home deposit.

"There are supply factors and there are demand factors. And one thing the federal government could do that would ease some of the demand pressure is to scale back immigration at least until land release and infrastructure can keep up," Mr Abbott told reporters on Monday night.

"And frankly there is nothing sacrosanct about any particular immigration number. The Howard government scaled back immigration its first few years for a whole host of reasons."