The prime minister pointed to federal government schemes to help first home owners and renovators as actions to curb the affordability crisis.

"Buying a home is never easy," he told Melbourne radio 3AW on Wednesday.

"Everyone who has gone through that at whatever stage of life. It's very, very difficult."

The First Home Loan Deposit Scheme will this financial year offer 10,000 eligible buyers a chance to enter the market with as little as a five per cent down payment.

An initial round offering the same amount of places was filled within two months of opening.

The scheme was expanded in the last federal budget alongside a new program to allow single parents to build a new home or purchase an existing home with a deposit of as little as two per cent.

"That's making a huge difference for first home buyers," Mr Morrison said.

He said the now-closed HomeBuilder scheme, which provided grants for building new homes or major renovations, had been a success.

"Our Home Builder program, which was rubbished by the Labor Party, has got tens of thousands of people particularly into their new homes."

Earlier in the week, global credit rating agency Moody's analysts said housing affordability had deteriorated over the past year with Sydney and Melbourne the worst hit.

It warned an inflation shock in Australia would make it even harder for people to enter the housing market if it resulted in higher interest rates.

On Wednesday, the government introduced a bill to parliament to increase the limit on the maximum amount of voluntary contributions made over multiple financial years that are eligible to be released under the First Home Super Saver Scheme from $30,000 to $50,000.

Australian Associated Press