WELLINGTON: New Zealand's daily coronavirus cases jumped to their highest level in weeks on Wednesday, a setback to the South Pacific nation's battle to eliminate the highly infectious Delta variant from its shores.

Health authorities reported 45 new cases, all in the biggest city, Auckland, taking the total number of cases in the current outbreak to 1,230.

It's much higher than the eight reported on Tuesday, and the highest number of daily cases since Sept 2.

COVID-19 Response Minister Chris Hipkins urged New Zealanders to stay calm, saying: "We do expect from time to time there will be blips."

Hipkins said at least 33 of the new cases are known household or close contacts of existing cases and most have been isolating at home or in quarantine facilities while infectious.

"I would encourage people not to read too much into it. We are still aiming to run this into the ground," Hipkins said at a news conference.

The continuing emergence of daily cases has raised questions whether New Zealand can eliminate the virus.

A top health official said last week that the country may never be back to zero cases again.

New Zealand eliminated COVID-19 last year and remained largely virus-free until an outbreak of the Delta variant in August led to a nationwide lockdown. Auckland has been in lockdown for over a month.

A delayed a vaccine rollout, however, means more people are at risk in the latest outbreak.

Ardern is now facing pressure from expatriate Kiwis and their families back home to drop her "zero tolerance" strategy and reopen borders.

The opposition National Party said on Wednesday that it would end lockdowns and reopen borders before Christmas.

"Delta is here, it may not be possible to eliminate it, and it would almost inevitably arrive into the community again. Whatever happens, we need to reopen to the world and National’s plan outlines how we can do that," National Party leader Judith Collins said.

Ardern has announced a phased reopening plan for early next year.