Police have charged Tarrant with murder following last Friday's shootings at two Christchurch mosques that killed 50 worshippers and injured dozens more.

Born and raised in Australia, the 28-year-old worked as a personal trainer in the NSW town of Grafton until about 2012, before travelling extensively in Asia and Europe before settling in Dunedin, south of Christchurch.

Ardern said she had a sense that Australians, like New Zealanders, are uneasy with the accused shooter's background.

"We're incredibly aware that Australians will be feeling that too," she said.

"We have acknowledged that this person was not a New Zealand citizen. They did not grow up with this ideology here. They did come to us and bring this terrorist act with them.

"But we do not see that as a reflection of our relationship with Australia or its people. And so I do draw that distinction. I think New Zealanders draw that distinction."

Ardern said she has spoken numerous times with her Australian counterpart Scott Morrison since the attack.

Ardern has also spoken with opposition leader Bill Shorten and Australia's high commissioner to New Zealand, Patricia Forsythe.

She praised the "fantastic" support from various Australian agencies.

Ardern confirmed she had postponed a visit to Australia planned for next week.

Australian Associated Press