New Zealand Prime Minister Jacinda Ardern said the country has "fundamentally changed" since the Christchurch shootings a year ago, as the coronavirus pandemic loomed over a planned weekend memorial.

Ardern said engagement with the Muslim community had grown since the massacre, but much more needs to be done to stop radicalisation in the country.

The memorial event on Sunday is still scheduled to go ahead, but she acknowledged that could change quickly if the coronavirus situation worsened.

To date, five New Zealanders have tested positive but Ardern said she will likely announce new border restrictions next week.