WELLINGTON, New Zealand — New Zealand’s largest city, Auckland, will remain in the strictest type of lockdown until Sept. 21 after the government on Monday reported 33 new COVID-19 infections.

Prime Minister Jacinda Ardern said lockdown restrictions were working to eliminate the outbreak of the highly transmissible delta variant.

“We don’t want to risk the sacrifices everyone has made and all the hard work you’ve put in by moving to Alert Level 3 too quickly,” Ardern said, referring to a relaxation of Auckland’s Alert Level 4 restrictions.

The rest of New Zealand will remain on Alert Level 2 until next week because of the risk of COVID-19 spreading from Auckland, she said.

“While there is an outbreak in Auckland that continues to produce cases, there is risk,” Ardern said.

The nation since last month has been battling an outbreak that came from Australia. The outbreak had grown to 955 cases by Monday with 21 infected patients in hospital and four in intensive care.

The government is pursuing an unusual strategy of trying to eliminate the virus entirely.