New Zealand will ease coronavirus restrictions in its biggest city from Wednesday as vaccinations rates rise and lockdown measures will likely be phased out by the end of the month, Prime Minister Jacinda Ardern said.

The city of Auckland has been in lockdown for nearly three months as the infectious Delta variant of the coronavirus spread, infecting more than 4,500 people since August in New Zealand's worst phase of the pandemic.

But a pick-up in vaccination rates and mounting pressure from critics calling for more freedoms, have prompted Ardern to end the curbs.

"Auckland has worked so hard to get their vaccination rates high, they deserve to be able to move as soon as they hit those targets regardless of what's happening in the rest of the country," Ardern told a news conference on Monday.

Auckland's vaccination rate rose to 90% for first doses over the weekend, Ardern said, and there is a strong expectation it will reach a target of 90% for second doses by Nov. 29.

Once Auckland reaches that 90% second-dose target, it will move into a new "traffic-light" system to manage outbreaks rather than tough lockdown measures.

Ardern said shops and malls can reopen in Auckland from Wednesday. Libraries, museums and zoos can also open and outdoor gatherings of up to 25 people will be allowed.

But the border controls between Auckland and the rest of the country remains in place and a decision on when this will be eased will be announced next week, Ardern said.

Once the poster child for stamping out COVID-19, New Zealand has struggled with the Delta variant, particularly in Auckland, forcing a rethink of a strategy to eliminate the virus.

(Reporting by Praveen Menon Editing by Robert Birsel)