An increase in new coronavirus cases has been reported in New Zealand on Monday, all in its largest city Auckland which is struggling to control the spread of the highly infectious Delta variant.

Health authorities has recorded 33 new cases of the Delta variant of COVID-19 on Monday, higher than 23 and 20 cases reported over the weekend.

Prime Minister Jacinda Ardern released the latest cases ahead of an announcement at 0400 GMT on whether the social restrictions in place in Auckland would be eased or extended.

The new cases take the number of confirmed cases in the new outbreak to 955, most of which have been in Auckland.

New Zealand was largely virus-free for months. An outbreak of the Delta variant imported from Australia prompted Ardern to order a snap nationwide lockdown on Aug. 17.

Last week, the lockdown was lifted in the rest of the country but Auckland remains shut, with schools, offices and public venues shuttered and its 1.7 million people ordered to stay indoors.

COVID-19 experts in the country have said it was unlikely Ardern would ease the restrictions in Auckland.

Otago University epidemiologist Michael Baker said to the state broadcaster TVNZ that although the Auckland outbreak seems to have passed its peak, there are still risks.