The move freezes the assets of Brenton Tarrant, who was given life imprisonment without the possibility of parole at an emotional High Court sentencing last week.

It will also make it a criminal offence to support his activities.

Prime Minister Jacinda Ardern said it was the first time New Zealand had added an individual to the list.

"Designating the offender is an important demonstration of New Zealand's condemnation of terrorism and violent extremism in all forms," she said.

"This designation ensures the offender cannot be involved in the financing of terrorism in the future.

"We have an obligation to New Zealand and to the wider international community to prevent the financing of terrorist acts."

Tarrant joins 19 other entries - including Islamic State, Al-Shabaab and other terrorist movements - on the designated list.

Ms Ardern said her government was open to designating further right-wing extemists of Tarrant's ilk.

The Labour leader has also confirmed her decision to meet with Tarrant's surviving victims to discover their views on whether she should seek the 29-year-old's repatriation across the Tasman to serve his punishment in an Australian jail.

Australian PM Scott Morrison has left the door open for this move.

"We both understand that there is currently no basis at law for it," she said.

"I would like to talk to the families before taking a particular stance on the issue."

Australian Associated Press