Declaring rich countries must do more not less, and that refugees are victims rather than the causes of violence, Mr Obama said governments proposing to build walls and close doors inevitably imprisoned their own citizens while ensuring they would be harshly judged by history.

"This crisis is a test of our common humanity - whether we give in to suspicion and fear and build walls, or whether we see ourselves in another," he said.

It came as an Essential Research poll released on Wednesday found 49 per cent of Australians support a ban on Muslim immigration, including 60 per cent of Coalition voters, 40 per cent of Labor voters and 34 per cent of Greens voters.

The most common reasons for wanting a ban were fears over terrorism, and a belief that Muslim migrants do not integrate into society nor share Australian values. The poll was first conducted in early August and then repeated to ensure it was not a rogue.

"It's too a big a number to say it's an unrepresentative rump that should be shunned from polite society," Essential pollster Peter Lewis told Fairfax Media.

In a strident call for more decisive action to help the world's 65 million asylum seekers and internally displaced persons, the US President used his opening address to an invitation-only summit on refugees in New York to pour scorn on the moral abandon propelling right-wing populists, such as US Rebublican presidential candidate Donald Trump, former UK Independence Party leader Nigel Farage and others in Europe, and Australian senator Pauline Hanson.

"It's a test of our international system where all nations ought to share in our collective responsibilities, because the vast majority of refugees are hosted by just 10 countries who are bearing a very heavy burden - among them Turkey, Pakistan, Lebanon, Iran, Ethiopia. Countries that often have fewer resources than many of those who are doing little or nothing," he said.

The Essential poll, with a typical sample size of more than 1000, came a week after Senator Hanson's incendiary first speech in the Senate in which she proposed that Australia halt Muslim immigration and stop building mosques and Islamic schools.

The poll found a high level of support for the One Nation firebrand, with two-thirds of voters agreeing she talks about issues other politicians are afraid of tackling, and 48 per cent endorsing a national debate about Muslim immigration.

Mr Lewis said the results showed mainstream political parties needed to re-engage with "outsider politics" as disenfranchised voters flocked to the fringes.

"It's consistent with a sense that the fault lines in the current political climate are not between the two major parties - they're between insiders and outsiders," he told Fairfax Media.

"If you look at the movements in the States, in Britain, the economic disenfranchisement drives a set of conversations around culture and difference that manifest at the moment in these sorts of positions."

If the poll is an accurate reflection of Australian voters, it highlights a significant hardening in anti-Muslim sentiment. A Roy Morgan poll conducted in October last year found broad support for Muslim immigration, with 28 per cent of respondents declaring themselves opposed.

The Obama comments came as Prime Minister Malcolm Turnbull revealed his government would dial up its refugee intake but was also ratcheting up the pressure on Iran to take back persons deemed not to have legitimate refugee claims, in a bid to clear out the detention centres on Manus Island and Nauru - the blight on Australia's international reputation.

"It's very important that nations accept back, whether on a voluntary or involuntary basis, their citizens who have been denied refugee status," Mr Turnbull said at a United Nations press conference held on the banks of the East River.

"This is a keen issue with a number of countries who will not do that and of course it is important that if there is going to be the co-operative action to end the scourge of people smuggling - and there is a global commitment, I believe, to do that - then there are a number of measures that have to be undertaken. One of them is to be prepared to accept the return of a nation's own citizens.

Reluctant to name individual countries, he eventually yielded, declaring: "I am certainly in contact with my Iranian counterpart over this issue. It's been a long-running discussion; we will continue to seek to negotiate with Iran so that they take back Iranian citizens who are found not to be owed protection. The simple fact is, they are Iranians who have been found not to be refugees, they must go back to Iran."

Mr Obama cited the treatment of the Jews by Nazi Germany, and the refusal of third countries to take in those fleeing that genocidal regime, to declare that failure to help people escaping current conflicts would leave a similar stain on our collective conscience.

Thanking Germany, Canada, and Australia, among other nations for their leadership in addressing the refugee crisis, Mr Obama nonetheless criticised the international community for doing too little to fix the root causes of displacement - singling out the faux co-operation over achieving a peaceful resolution to the Syrian civil war.

And in a direct repudiation of the Trump/Hansonite philosophy of ending Muslim immigration and refusing refugees from countries suffering from extremist problems, Mr Obama pledged the opposite response.

"In the coming fiscal year, starting next week, the United States will welcome and resettle 110,000 refugees from around the world - which is a nearly 60 per cent increase over 2015. We intend to do it right, and we will do it safely," he said.

He said the use of people smugglers exposed refugees and the target counties to "the same criminals who are smuggling arms and drugs and children".

"When nations with their own internal difficulties find themselves hosting massive refugee populations for years on end, it can risk more instability. It oftentimes surfaces tensions in our society when we have disorderly and disproportionate migration into some countries that skews our politics and is subject to demagoguery," he said, in an obvious reference to the outspoken Republican nominee.

"And if we were to turn refugees away simply because of their background or religion, or, for example, because they are Muslim, then we would be reinforcing terrorist propaganda that nations like my own are somehow opposed to Islam, which is an ugly lie that must be rejected in all of our countries by upholding the values of pluralism and diversity.

"We cannot avert our eyes or turn our backs.  To slam the door in the face of these families would betray our deepest values. It would deny our own heritage as nations, including the United States of America, that have been built by immigrants and refugees. And just as failure to act in the past - for example, by turning away Jews fleeing Nazi Germany - is a stain on our collective conscience, I believe history will judge us harshly if we do not rise to this moment."

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