Key Points:

The National Party has promised to keep at least the existing number of state houses if it wins this year's election.

Housing spokesman Phil Heatley told a Housing Institute seminar in Waitakere yesterday that National would give back to Housing New Zealand tenants the right to buy their houses.

They had this right until the Labour Party won the 1999 election.

But he said National would not sell state houses to outside investors, as it did in the 1990s, and would use the proceeds of sales to tenants to buy or lease new state houses.

"If they purchase their state home, we will replace that home within the housing stock so as to lift someone else off the waiting list," he said.

"We won't be running down the state housing stock. We acknowledge that we need it."

National leader John Key, who grew up in a state house in Christchurch, has already signalled that National's policy this year will be softer than in the 1990s, when it put all state tenants on market rents and introduced an "accommodation supplement" to help people on low incomes equally in both state and private homes.

Mr Heatley said the party would now keep Labour's policy of fixing state house rents at only 25 per cent of the tenants' incomes except for tenants on high incomes.

Labour's Housing Minister, Maryan Street, told the seminar that 9 per cent of Housing NZ tenants already paid market rents because of their high incomes.

Mr Heatley said that meant that about 6182 of the current 68,686 tenants were earning high enough incomes to be able to aim to buy their own houses.

"Not all of them could afford to buy their own home, but there are hundreds who are paying market rents on incomes of $60,000 to $80,000 a year. I know this because I have asked for the figures," he said.

"Is it a silver bullet? No. But if they want to get into home ownership we will back them."

Ms Street said National had reduced the number of state houses by 13,000 from a peak in 1993, and Labour had built up the number again by 8000 since 1999.

"It costs more and takes longer to build a state house than it does to sell one," she said.

"We haven't even recovered back to where we were in [1993]. We have a state house waiting list of just under 10,000. If we had those 13,000 homes, we perhaps wouldn't have a waiting list.

Mr Heatley refused to commit National to continuing to increase the state housing stock, pointing to "inefficiencies" such as one or two parents left in large family homes where the children have all left, and state houses valued at $750,000 or $1 million which could be sold to fund several cheaper houses.

He promised to keep the accommodation supplement.

He also promised to keep Labour's Housing Innovation Fund, which provides $12 million a year in capital for community groups providing shared-equity and other subsidised housing to low-income people.

But he said this might need to be restricted to groups that were big enough to get the economies of scale that came with a decent-sized housing business.