Biosecurity New Zealand intends to liberalise import regulations to allow uncooked pork in to New Zealand. It says it will only allow consumer-ready cuts, or pork which can be cut down to consumer-ready cuts. That way the pork meat is unlikely to be fed to pigs which can pass on the virus from infected meat, MAF says.

At the moment, pork imported into New Zealand from countries with PRRS has to cooked, or subjected to pH levels that kill the virus.

Professor Roger Morris, from Massey's EpiCentre, says he is very concerned about the proposed changes, which threaten New Zealand's pork production industry.

PRRS has been associated with up to 70 percent of piglets dying before weaning, and a further 15 percent dying post-weaning.

The onus will fall on pig owners to make sure biosecurity regulations are upheld.

"This is a massive policy change without public discussion. What MAF is doing is moving away from protection before or at the border, to totally relying on protection by individuals within the country."

Prof Morris says while there are 250 commercial pig raisers and they would never dream of feeding uncooked meat to pigs, there are thousands of people who have only a couple of pigs.

The industry cannot control them all and biosecurity should not be the responsibility of individuals, he says.

The pork industry and Prof Morris are worried the easing of regulations may also open the door for other exotic diseases.

MAF did not look at other diseases when it did its risk analysis, he says.

"In Asia, for instance, there can be claims that a country is Foot and Mouth Disease free, when it may not be reliably free. In the future, they could export to New Zealand.

"There are a number of diseases, other than PRRS that MAF really should have looked at before deciding on any change."