Refugee advocates say the Australian government has only accepted a resettlement deal with New Zealand because the issue had become "politically untenable" with the election looming.

On Thursday, Immigration Minister Kris Faafoi announced Australia had accepted New Zealand's longstanding offer to resettle up to 150 refugees a year.

The three-year deal will cover refugees from detention centres in Nauru or Australia, and be screened by the United Nations refugee programme and vetted by New Zealand authorities.

Former prime minister John Key first made the offer to then Australia prime minister Julia Gillard in 2013, as international scrutiny of Australia's offshore detention centres ramped up.

The offer followed Helen Clark's in 2004 to take in refugees from the Tampa ship, who had been rejected by Australia.

Meg de Ronde, executive director of Amnesty International New Zealand. Photo / Supplied

In 2017, one of Jacinda Ardern's first actions as Prime Minister was to renew the offer to then-prime minister Malcolm Turnbull at an international summit, but it was turned down again.

For years, Australia maintained refugees held on those offshore could never be resettled in New Zealand.

Arguments were that New Zealand would be a "pull factor" or create a "back door" entry to Australia.

Faafoi said the delay was because Australia had deals with the United States and Canada. Once those expired, Australia approached New Zealand about taking up the offer, he said.

But advocates say none of those reasons stacked up, and those nine years had been "nine years of harm and wasted lives" for those who remained detained in the centres.

Amnesty International New Zealand executive director Meg De Ronde said they welcomed the news and congratulated all those involved in what had been a "really long process".

"But it cannot be ignored it's become a political issue, and it is becoming politically untenable - what they are doing is abhorrent."

While there was once political support in Australia for its hardline stance on asylum seekers and refugees, which contravened international law, situations like medevac from Papua New Guinea had brought the practices to Australia's doorstep.

The situation of Novak Djokavic had also thrown the policies into the international spotlight.

All this was happening in the lead-up to Australia's federal election in May.

"Nauru [detention centre] should close and we should continue to pressure on our side.

"But this is a difficult political issue and Australia is still talking tough about breaking international human rights laws."

New Zealand-based Iranian journalist Behrouz Boochani, who spent six years detained at the Manus Island detention centre in Papua New Guinea, said he was "very happy" with the news.

"It will give those refugees an opportunity to establish a new life. It also sends a message that this country respects human rights and is willing to help."

Boochani got a temporary visa to fly to New Zealand in 2019 as a guest at a writers' festival, and lodged a claim for protection when he arrived. He was granted refugee status last year.

Behrouz Boochani, the Kurdish film-maker, writer and refugee who came to New Zealand in 2019. Photo / AP

Boochani said more pressure needed to be put on Australia to close the detention centres for good.

"Australia has been violating human rights in the region for years, torturing refugees, jailing refugees, separating families - it needs to stop. New Zealand has a duty to stand up."

Boochani said Australia's fears about refugees using New Zealand as a "backdoor" was a lie to cover up a political excuse.

"Anyone who comes here, why would they want to leave and go to Australia, which has treated them like that? It is quite an insulting comment."

Green Party human rights and refugee spokeswoman Golriz Ghahraman said the deal should come on top of the existing quota, which New Zealand had not met for three years due to the pandemic.

Since July 2019, just over 1500 quota refugees have arrived here, out of 4500 spaces.

Last year just 263 arrived. Additionally, spaces for 300 family members a year have not been filled; just 164 have arrived over the past nearly three years from 900 spaces.

Ghahraman said New Zealand needed to do more to pressure Australia to shut its offshore detention centres permanently.

"We have our closest ally, right next door, holding people in conditions that have been described by the likes of Amnesty International and the United Nations ... as being akin to torture.

"Australia is torturing people right next door in our Pacific neighbourhood. New Zealand needs to be a very loud voice of criticism and work constructively to shut down the centres."

According to the Refugee Council of Australia there were 105 people at facilities in Papua New Guinea and 114 on Nauru, as of December 31.

There were also 104 still in Papua New Guinea not included in the deal.

Jana Favero, of the Asylum Seeker Resource Centre (ASRC) in Australia, said there were still an estimated 1384 people seeking asylum and refugees subjected to offshore detention since 2013 who were either in Australia or held offshore.

The 450 places offered through the New Zealand deal was positive but there would still be around 900 without a clear resettlement option, she said.

"This deal is positive, but it was initially offered nearly a decade ago in 2013, and it should have been accepted back then.

"There has been nine years of harm and wasted lives because this deal was not accepted when first offered.

"This deal will also still leave behind hundreds of people who sought safety in Australia.

"The Morrison Government must offer a permanent resettlement plan for everyone who was subjected to offshore detention."

Australia's Minister for Home Affairs Karen Andrews said despite the deal their "strong border protection policies had not changed and no one who attempted to travel to Australia illegally by boat would ever settle here".

"This arrangement does not apply to anyone who attempts an illegal maritime journey to Australia in the future.

"Australia remains firm – illegal maritime arrivals will not settle here permanently.

"Anyone who attempts to breach our borders will be turned back or sent to Nauru."