[2 photos with this article, one presumably of Donald Young and truck titled "Degradation to jubilation ...Donald Young's property in Central Otago was the first to be found with the disease"-Fotopress picture and "Dead rabbits adorn a fence at Lowburn" with four dead rabbits hanging by their ears from a wire fence"]

Road blocks were set up and aerial searches conducted across the South Island of New Zealand yesterday in an attempt to control the apparent illegal introduction of the rabbit calicivirus disease, believed to have spread from Australia.

The disease has killed up to 180 million rabbits across Australia since it was accidentally released from a research station in early 1995, which was followed by controlled releases and has led to widespread revegetation across wide sweeps of arid country.

When the NZ Government refused to release the virus last month, citing unknown consequences, angry farmers threatened to release it illegally.

Rabbits infest much of the New Zealand high country in both the North and South islands.

On Tuesday, six samples from three dead rabbits found on a Cromwell, Central Otago, property in the South Island tested positive for calicivirus. Four farms in the area were placed under quarantine immediately.

Officials were also checking rabbit corpses in the Twizel and Maniototo areas in the lower central South Island and conducting helicopter sweeps of suspected outbreak sites hundreds of kilometres apart.

"It appears this disease has been deliberately and illegally introduced," said the Ministry of Agriculture's chief veterinary officer Barry O'Neil.

Farmers Federation spokesman Mr Edward Orr said that while the federation did not support illegal introduction of a biological control agent, it always had believed it would arrive accidentally or intentionally.

"A number of farmers on the brink of disaster from the degradation caused by rabbits are delighted to see a new tool to destroy this rodent," Mr Orr said. "That is why we are happy. I would be too."

Farmer Geoff Brown, from Lowburn in Central Otago, described the calicivirus devastation as "the greatest day of my life".

Liz Brown, from Luggate, north of the outbreak said, said: "I hope it is very virulent and spreads like hell. I can't remember when I felt this excited. Its better than Christmas."

Chairman of the Australian calicivirus management group, Mr Graham Eggleston said that with more than a dozen daily flights between Australia and New Zealand and the disease's spread requiring only part of an infected animal, it would be almost impossible to determine how the virus got to New Zealand.

He said if the New Zealand Government found it impossible to eradicate, Kiwis would now have to consider how best to make use of it.

Head of livestock for NSW Farmers, Mr Mick Keogh, said "We can understand the frustration of the NZ high country farmers who, like Australian producers, see rabbits as a major environmental pest and require tools to assist in their eradication".

End