A controlled release of the rabbit-killing calicivirus will happen this month in Northland.
People with pet rabbits are being warned to make sure their animals are vaccinated.
Mike Knight, a Kaitaia-based pest management officer with the Northland Regional Council, said the virus occurred naturally among wild rabbits in Asia and Europe but
was introduced into New Zealand illegally in 1997.
The use of the calicivirus has been legalised subject to strict conditions.
The NRC makes up a consortium of 10 regional council and two unitary authorities, which several years ago gained approval to import the virus from Australia and register it in New Zealand as a "rabbit biocide".
Mr Knight claimed calicivirus was already widespread in Northland but said it was species-specific and targeted only adult rabbits.
He said it posed no risk to humans and other animals.
"At this stage, we're currently assessing areas where medium to heavy infestations have been reported to determine where the virus will be released, but it looks likely there will be three main releases in the Ahipara, Taupo, Opito Bay and Kerikeri areas."
He said rabbits were already dying from the infection in Northland every year, but that pockets of low or nil infection still existed and this is why he believed a release was necessary.
The council's last release of the virus in Northland was in 2006.
Mr Knight claimed it reduced populations in some areas but that rabbit number in other areas had increased.
He believed the release later this month would reduce rabbit numbers by 40 to 60 per cent.
He said only qualified staff would be involved in the release.
Bait releases involved diced carrots laced with a solution containing the virus.
He urged people with pet rabbits to contact their vet to arrange for them to be vaccinated ahead of the release. It costs about $30.
