The New Zealand racing industry is on tenterhooks on Monday as Australia's equine influenza outbreak worsens.

As of early Monday, there has been no evidence of the disease in New Zealand, but MAF Biosecurity is promising to be vigilant in its efforts to keep it out.

On Saturday it banned horse imports from Australia and on Sunday tightened up on its border control procedures relating to people who have been in contact with horses in Australia.

The situation has worsened in Australia, after news broke of the outbreak of the disease in Sydney late on Friday. All horse race meetings, bar in the Northern Territory, were cancelled at the weekend and a 72-hour lockdown on horse movement remains in place.

It is due to expire on Tuesday afternoon, but the indications are that a new, longer one will take its place, with the disease spreading from Sydney to rural NSW and three suspected cases reported in Queensland on Sunday.

"The 72-hour ban is still in place, but they (Australian authorities) have signalled that it may be necessary to extend this and there are some reports that 28 days would be the next step they extend to," MAF Biosecurity assistant director-general Barry O'Neil told NZPA on Sunday night.

In New Zealand, preliminary inquiries had identified 97 horses that have been imported from Australia since August 1.

MAF's focus is on those that arrived in the past 11 days. He said there were 16 horses on the last known flight into New Zealand last Monday.

"In some cases, these horses have already been inspected by the owners' veterinarians; we have talked to the owners over the phone to identify what the risk situation could be with the animals."

He said the horses would not be tested unless there were clinical signs of the disease.

MAF is stiffening its border control procedures around the importation of horse equipment.

Humans can carry traces of the disease for up to 36 hours and they can remain live on horse equipment.

"All horse equipment that arrives in New Zealand from Australia will be directed...to a treatment facility for cleaning, disinfection and/or fumigation.

"Passengers entering New Zealand from Australia from will be questioned as to their movements within the country. If they have come from and visited an infected area they will be questioned further and may have their personal luggage searched."

O'Neil said a comprehensive response plan was in place and two vaccines were registered for emergency use, should the disease be found in New Zealand.

"There are currently no plans to vaccinate horses in New Zealand as a precautionary measure."

O'Neil said New Zealand was working closely with Australian authorities and would review the situation over the next two or three days as more information came to light.

Six stallions due to spend the spring breeding season in New Zealand are stranded in Australia, while some Kiwi broodmares are also there, waiting to be served by Aussie sires with the breeding season due to start on Saturday.

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