The National Party says it brought forward the release of two of its key policies before they could be leaked by Labour.
Cabinet minister and Labour Party MP Trevor Mallard on 9 September released the third National policy in a week, saying they are being drip-fed to him.
But National insists someone left a bundle of documents lying around Parliament, containing a number of policies.
Later that day National released its housing policy and building and construction policy, which it believes Mr Mallard may have had copies of.
National says keeping the New Zealand dream of home ownership within reach is a central focus of those policies.
The housing policy will allow state house tenants to buy the house they live in and maintain the state housing stock by reinvesting all money from these sales in replacement houses.
National's building and construction policy promises to cut back on red tape in the building industry and drive quality by encouraging warranties, better standards and improved skills.
National policies leaked
Mr Mallard released National's Research, Science and Technology policy after leaking its environment and conservation policies last week.
National confirmed on 9 September it would scrap the Government's $700 million Fast Forward Fund for primary sector research and has instead proposed an International Centre of Research and increased funding.
The policy also includes restricting the existing research and development tax credit and using the $100 million saving to boost funding.
The Government says it is horrified by National's policy. Prime Minister Helen Clark says the Fast Forward Fund is very important to New Zealand's future and National also plans to axe successful research and development tax credits.