Prime Minister Malcolm Turnbull has announced Australia will take refugees from Central America as part of its annual intake, which will remain at the 2018-19 goal of 18,750.

Key points: Australia will help resettle refugees fleeing violence in Guatemala, Honduras and El Salvador

Australia will help resettle refugees fleeing violence in Guatemala, Honduras and El Salvador Mr Turnbull also said annual refugee intake would stay at 18,750

Mr Turnbull also said annual refugee intake would stay at 18,750 That announcement criticised by Bill Shorten, aid groups

Mr Turnbull made the announcement during an address at a United Nations General Assembly meeting in New York, convened by US President Barack Obama, aimed at finding a better international solution to deal with 65.3 million people displaced around the globe.

But Opposition Leader Bill Shorten labelled the announcement on the intake numbers as a "hoax", saying the Prime Minister had "reheated the leftovers" from Tony Abbott's policies.

The US earlier this year announced a plan for Costa Rica to temporarily take refugees fleeing violence in Guatemala, Honduras and El Salvador.

Mr Turnbull said Australia would help the US resettle some of this group.

"We will also participate in the US-led program to re-settle Central American refugees currently in a re-settlement centre in Costa Rica," he said.

"Australians support these actions because they have confidence that our migration system is well managed."

People swap with Manus, Nauru refugees ruled out

Mr Turnbull told the invitation-only meeting Australia's humanitarian intake would remain at 18,750 on an ongoing basis.

Former PM Mr Abbott initially announced the rise — up from 13,750 — would be achieved in 2018-19, but did not make clear whether the increase would be permanent.

Mr Turnbull told reporters in New York there was no plan to increase Australia's intake beyond the 18,750 figure, describing it as "sustainable and maintainable".

The figure remains below the 19,998 intake reached in 2012-13, when the Government took onshore applications from people who had arrived by boat. Just under 40 per cent of the available visas were granted to onshore applicants.

"Obviously governments have the absolute right to review it and adjust it, either up or down as circumstances change," he said.

"A lot of people say 'Australia is a big country, we've got lots of room'.

"The reality is that one of the features of the Australian migration story — and we are a nation built by immigration — is that we have done a very effective job over many decades, of settling our migrants, ensuring that they are integrated, and of course the ones that have the greatest challenge are very often the refugees."

Special Minister of State Scott Ryan ruled out a people swap in terms of the refugees and asylum seekers currently on Manus Island and Nauru when taking in refugees from Central America.

"There is no basis at all for this allegation of [a] people swap," he told the ABC.

"There will not be a people swap."

Mr Turnbull also announced funding for refugee programs would be increased by $130 million over three years.

He said the funds would help support peace building and give assistance to refugees and forcibly displaced communities in host countries.

Announcement doesn't solve real problem: Shorten

Addressing reporters in Adelaide, Mr Shorten called on the Coalition to spell out the negotiations its ministers had with other countries.

"Malcolm Turnbull has flown to New York to reannounce Tony Abbott's policies," he said.

"They haven't dealt with the elephant in the room … The fact that we have nearly 2,000 people trapped in indefinite detention on Manus [Island] and Nauru."

Mr Shorten also called for more information over what he called the "Costa Rica solution".

Greens' immigration spokesperson Nick McKim also criticised the Prime Minister for not addressing the situation on Manus Island and Nauru, saying Australia had a legal and moral obligation to resettlement those on the islands.

Senator McKim said pledging to take in refugees from Central America without increasing the overall humanitarian intake further would mean others in the region would miss out on resettlement opportunities.

The re-announced figure remains below the 19,998 intake reached in 2012-13, when the Government took onshore applications from people who had arrived by boat.

Aid agencies also sceptical

Mr Turnbull's announcement has also been downplayed by aid agencies, with Oxfam stating that there was "no actual increase" in the intake.

Oxfam humanitarian advocacy lead Dr Nicole Bieske told ABC NewsRadio the number fell "significantly short" of what Australia should be accepting.

"We're not satisfied with that figure ... that's actually an announcement that the former Prime Minister Tony Abbot made last year, that the number would increase to 18,750, and what Prime Minister Turnbull has announced is that that will continue beyond 2018.

"From Oxfam's perspective we've got modelling that shows that our humanitarian intake actually should be increased up to 42,000 people.

"We know that in the past we've accepted far more refugees.

"In 1980 we actually accepted nearly 23,000 people. If you model up for population and model up for economic growth, we think that we would come very close to the number that we are calling for now."

In a statement, Oxfam chief executive Dr Helen Szoke said it was "step in the right direction but not a new announcement".

Refugee Council president Phil Glendenning also told the ABC it was wrong for Australia to claim it is among the most generous nations in assisting refugees.

"In terms of the dozen or so countries that are part of the UN's formal resettlement program, Australia ranks third, that's true," he said.

"But if you weigh that up against the burden that's put on, particularly third world countries and countries close to conflict zones, we shouldn't kid ourselves that we're actually in the front line of sharing the burden on this, we're not."