Barnaby Joyce has warned New Zealand to mind its own business on border protection after its prime minister offered to take 150 refugees from Manus Island.

Jacinda Ardern's offer has been repeatedly rejected by the Turnbull government over concerns it might provide a back door into Australia.

Asked whether New Zealand should back off, Australia's deputy prime minister told Kiwi radio station Newstalk ZB: "It's best if you stay away from another country's business."

"Because otherwise they will return the favour at a time they think is most opportune for them."

New Zealand Prime Minister Jacinda Ardern (left) and Australian Deputy Prime Minister Barnaby Joyce. (AAP)

Mr Joyce, who was recently re-elected to his NSW seat of New England after being disqualified for holding New Zealand citizenship, said other countries must be allowed to sort out their own issues.

"If you're going to talk to them at all, talk to them quietly and discreetly off the record," he said.

But Ms Ardern said Australia was being overly sensitive on the issue.

"I haven't raised this as an issue for weeks. I've been asked questions because my Australian counterparts have spoken of it, that is the only reason," she told reporters in Wellington on Wednesday.

NZ opposition leader Bill English said Mr Joyce's comments showed strain in the relationship between the two countries.

"The prime minister's campaign on Manus Island I think has gone further than making her own point and is probably creating some tension in the relationship," he said.

He has previously labelled the offer - first extended by then National prime minister John Key and later by Mr English himself - a "crusade" for Ms Ardern's domestic audience.