New Zealand's Prime Minister Jacinda Ardern has said the strict nationwide lockdown enforced to stamp out Covid-19 is helping limit the spread of the highly infectious Delta variant, even as the number of new cases are rising.

New Zealand has reported 68 new cases, taking the total number of people infected in the latest outbreak to 277, according to Reuters. Of the total cases, 263 are in Auckland and 14 are in the capital, Wellington.

The entire country of five million is under stay-at-home orders, with schools and most workplaces closed until at least the end of the month.

"Lockdown is having an impact but Delta is very tricky," Ardern said at a news conference. "We do need to be incredibly vigilant."