Party co-leader and genetic engineering spokesperson Jeanette Fitzsimons was responding to suggestions made by Environmental Risk Management Agency (ERMA) chairman Neil Walter before a parliamentary select committee that it was possible the equine industry will lodge an application for the conditional approval of such a vaccine.
Fitzimons says news there may be an application for the first live GE vaccine in New Zealand will test the stringency of the law and its processes.
"It is worrying that the first off the blocks for release of GE may be a vaccine. These are often the most problematic of all organisms," she said.
"These types of vaccines are normally a GE virus or a bacterium; they cannot be seen and are impossible to recall if they turn out to have dangerous effects."
"They also may be able to live outside their intended host, or in another host. There may be no way to know what other animals might be infected with this organism.
"There is no further information on which to base more detailed appraisal, but if this application is made in election year we can expect the government to come under considerable pressure.
"The opposition to the release of GE organisms into the environment has not gone away, it has simply gone quiet because there have been no applications.
"The Green Party remains opposed to the release of any live GE organism and will make every effort to oppose any such application."
An equine flu vaccine that is not genetically modified has already been approved for use in New Zealand.
Any application in New Zealand may well be for the live ProteqFlu vaccine - the same vaccine which was crucial to the recent successful eight-month campaign in Australia to eradicate equine flu.
Meanwhile, there are signals out of Australia that its racing industry may want to have an ongoing flu vaccination programme to minimise the economic impact of any future possible outbreaks.
Racing New South Wales said it completed a review last week of its equine flu vaccination requirements "and reaffirmed a commitment to its risk management policy which requires all NSW-domiciled racehorses to have a current vaccination programme in accordance with Racing NSW Local Rule 48".
The policy, it said, was reviewable after the June 30 ruling on an application from Racing NSW for an extension of [state] permission to continue an EI vaccination programme in NSW with the genetically modified ProteqFlu Vaccine".
However, given that the live vaccine is not available in all states, exemptions can be granted for racehorses travelling to compete in NSW from other states.
Back in New Zealand, the Green Party has this week criticised the Biosecurity and Hazardous Substances and New Organisms Legislation Amendment Bill before parliament, suggesting it will become a backdoor to allowing unapproved genetically engineered organisms into New Zealand.
"The Bill will shift the responsibility for approving and controlling new organisms that arrive 'incidentally' - such as micro-organisms and insects infecting other goods - from the Environmental Risk Management Authority to MAF Biosecurity NZ," Fitzsimons said.
"This move can only weaken our protection from new organism threats which would threaten our primary production industries and our precious indigenous flora and fauna as it is common knowledge that the Hazardous Substances and New Organisms Act gives much greater protection than the Biosecurity Act," which she told Horsetalk was a "low hurdle to jump".
"This could apply to a live vaccine that came in inside a horse that had been vaccinated overseas. If this happened widely the vaccine would no longer be a new organism so would need no approval.
"At present GE organisms are not included in the legislation but it is clear from earlier papers that they are intended to be ..."
Thus, she said, the first GE organism could be released into New Zealand without even being scrutinised under the relevant legislation."