Malcolm Turnbull with then prime minister Kevin Rudd in March 2010. Credit:Glen McCurtayne Asked why refugees in a Costa Rican camp were deemed morally superior and could be granted the right to Australian resettlement whereas those in PNG and Nauru did not, Mr Turnbull let fly. "We have to recognise that in Australia, we don't theorise about people smuggling," he began. He said the boats had stopped under John Howard and there was no people smuggling but that Mr Rudd had been elected in 2007 and changed the policy settings creating a "pull factor" or incentive to attempt the vast and dangerous maritime voyage. "The Labor Party have that on their conscience, they made that decision, it defied reality, it defied common sense, they pressed ahead with it and 50,000 people arrived, 1200 at least, drowned at sea, $11 billion of expense. It was the biggest policy failure in the history of the Commonwealth – tragic, so many people died, that was the Labor Party's legacy," he said.

Prime Minister Malcolm Turnbull and Foreign Minister Julie Bishop listen during the 71st session of the United Nations General Assembly. Credit:Julie Jacobson "And you ask about the people on Manus Island and Nauru? Kevin Rudd put them there, the Labor Party put them there. We have been dealing with Labor's legacy, their legacy of shame. He said his government had closed 17 detention centres, removed "several thousand" children from detention under Labor. Kevin Rudd and UN secretary-general Ban Ki Moon at UN headquarters in New York last month. Credit:Trevor Collens "This is what we've had to deal with now we do not have to theorise about it, this is not a matter for academic speculation, we know exactly what works and what doesn't work," he said.

Meanwhile, almost two months after the government declined to nominate him for the UN secretary-general election, Mr Rudd has maintained that Mr Turnbull betrayed him and was justifying it with a "concocted excuse". In an interview with Sky News overnight, Mr Rudd said criticism of him - that he didn't have the character to lead the organisation - was invalid because Foreign Minister Julie Bishop privately and publicly advocated his candidature and the Department of Foreign Affairs and Trade also endorsed him. "We all know, in the case of Malcolm Turnbull, it's pretty simple," Mr Rudd said. "Malcolm felt the pressure of the hard right-wing of his party, having had a narrow win in the last election, and as a result of that, lost courage of his convictions, having provided me with multiple assurance privately over many, many months that he would be backing my candidature for the position." Former Labor leader and Australian ambassador to the US, Kim Beazley, recently said Mr Turnbull had expressed concerns to him about Mr Rudd's candidacy early this year, calling the Prime Minister's eventual rejection of his former rival "utterly consistent".

Mr Turnbull was speaking on his last day in New York before addressing the UN General Assembly and then heading to Washington to press legislators to back the Trans-Pacific Partnership, during the so-called "lame duck" session of congress. While officially he remains upbeat, as do senior Obama administration officials, few hold out realistic hopes of it actually happening. Australia has agreed in principle to resettle some Central American asylum seekers while attending Barack Obama's special refugee and displaced persons summit ahead of the UN meeting. More than 850 asylum seekers housed on PNG's Manus Island have been found to have legitimate refugee claims, but Australia has insisted they cannot be settled in Australia nor in any comparable standard country, for fear of providing a new incentive – or as the government puts it, a product to sell – for criminal people smugglers. The government maintains that no agreement has been reached with the US for the settlement of PNG or Nauru refugees, but hopes remain that Australia's gesture to Central America might prompt some reciprocal gesture in the near future.

In other comments, Mr Turnbull again appealed to larger powers such as the US and Russia to resist the tendency to fight a proxy war in Syria, saying it was vital that Islamic State be defeated and peace re-established. But fresh from more talks with Mr Obama on the sidelines of UN meetings, and with arguments raging internationally over horrendous civilian and aid workers deaths from errant air raids, Mr Turnbull appeared more despondent about resolving the long-running conflict. Loading with Fergus Hunter Follow us on Twitter