Wellington - The number of confirmed cases of the new influenza H1N1 in New Zealand has grown rapidly over the last few days to 86, up from 35 on Friday, the health ministry reported on Monday.

But it said the number remained "relatively few" and because the country was still in the containment phase there were only isolated instances of community transmission.

Health Minister Tony Ryall told a news conference the numbers were bound to increase and the ministry reported an additional 17 probable cases.

The ministry said better information about the incubation period of the disease means that only people who developed flu-like symptoms within four days of arriving in the country were now considered to be at risk.

Deputy director of public health Fran McGrath said it was business as usual for most workplaces, and staff should only stay home if they had flu-like symptoms or been given medical advice to do so.(dpa)