The Ministry of Agriculture and Forestry says the kiwifruit vine disease PSA may have been let into New Zealand by mistake.
In 2007, rules were changed to allow kiwifruit pollen to be imported, as it was then considered to be sterile and unable to carry PSA.
The research was carried out by the Ministry of Agriculture and Forestry, in conjunction with the Kiwifruit industry, after the vine disease hit last November, and spread to nearly a third of the country's kiwifruit orchards.
The ministry's director-general Wayne McNee says it is disappointing to discover the potential mistake, and he has ordered a review of importing rules.
Since the PSA outbreak, pollen can no longer be imported.
Mr McNee says it is unlikely the origins of PSA will ever be known for certain but he hopes the review, due to begin in the new year, will improve New Zealand's biosecurity.
Te Puke kiwifruit grower Michael Montgomery says he still wants answers as to how PSA came into the country.
He says there has been wide speculation that pollen imports carried PSA.
Mr Montgomery says the disease is here now and the damage has been done, but he would still like to know how it here.
