KEY POINTS:
MAF's equine quarantine facility at Karaka was off-limits last night after an equine influenza scare.
Emergency protocols were put in place after tests on 10 horses imported from the United States on March 23 suggested the presence of the virus.
It hit the eastern states of Australia last year, stopping horse racing for months and costing the Australian economy billions of dollars.
In extreme cases the virus is fatal.
MAF Biosecurity New Zealand announced yesterday that it was retesting samples taken from horses imported directly from the United States to the Karaka quarantine facility because of conflicting test results.
MAF says the horses tested negative before export but were positive when in quarantine in New Zealand.
The horses appear healthy and are not displaying symptoms of disease.
"There is a strong indication that cross-contamination in the laboratory was the reason for the positive results. The laboratory will be conducting further tests over the weekend to confirm this.
"Further investigations will also be made to ascertain how the tests in New Zealand became contaminated," said MAF's import standards group manager, Clive Gower-Collins.
As a precaution, MAF has moved quickly to isolate the Karaka facility. No horses will be allowed to leave or enter the site, and no visitors will be permitted entry.
"Current requirements are designed to identify unwanted viruses and diseases like influenza before horses are cleared. Under strict import standards horses are required to undergo 21 days' quarantine before departure for New Zealand, including testing and vaccination, and a further 14 days in post-arrival quarantine in New Zealand, where they undergo further testing.
"The horses have been in quarantine since their arrival from the United States in a secure facility, so there is no risk to the New Zealand horse population," said Mr Gower-Collins.
New Zealand Racing Board chief executive Graeme Hansen said: "The horses in question were picked upduring standard quarantine procedures and we are pleased that MAFBNZ have moved quickly and taken every precaution in the protection of our industry."
The Karaka facility is not at New Zealand Bloodstock's Karaka sales centre.
