New Zealand has made masks mandatory from Thursday for users of public transport in Auckland as well as on all domestic flights.
It comes after a new coronavirus infection was reported in the community last week.
According to the authorities, the positive test in a student was linked to a known case from a border isolation facility, suggesting less risk of a wider unseen spread.
"Adding mask-wearing to the toolbox of measures against the virus is a sensible precaution and the time is right to make the move," Health Minister Chris Hipkins told a news conference on Monday.
The rules take effect on Thursday for travellers older than 12 on public transport in and out of Auckland. Taxi and Uber drivers must also wear masks, although their passengers have been exempted.
Also exempt are children going to and from school, Hipkins said, adding that police could enforce the rules as a last resort.
Last week, the government said it was also considering mandatory use of a COVID-tracing app before entry to large events and hospitality venues.
With 1,645 infections and 25 deaths, New Zealand ranks among the lowest in the world in terms of virus fallout.