The Australian government has reportedly resettled as humanitarian migrants two Rwandan men who had been charged with murder, on request from the U.S. government.
Former prime minister Malcolm Turnbull struck the refugee deal with the previous U.S. president, Barack Obama, and convinced incumbent Donald Trump to stick to it.
Rob Haubner and Susan Miller were murdered by Rwandan rebels in 1999.
At the same time the Australian government was arguing against proposed legislation for evacuating sick refugees and asylum seekers from Manus Island and Nauru to Australia, claiming it would strip the government of the power to prevent murderers and other criminals coming into Australia.
"Allegations, I know, have been made out there in the public forum", Mr Morrison told the National Press Club in Canberra.
"But what I can assure Australians of is this - our government will always ensure that those character and national security considerations are undertaken for anyone who seeks to enter this country".
Mr Turnbull's successor as prime minister, Scott Morrison, has come under pressure to explain why Australia agreed to take in the alleged killers, but did not comment directly on the case.
Leonidas Bimenyimana and Gregoire Nyaminani were part of a trio who faced trial in the United States over their involvement in the murder of eight British, American and New Zealand tourists in Uganda in 1999, having confessed to the crimes, but the legal case fell apart and they have been in limbo since.
Despite taking two men, it was reported that Australia refused to take the third alleged killer, Francois Karake, as he was involved in a fight with a U.S. jail guard in 2015.
Jean and Peter Strathern of Christchurch told TVNZ they had not been officially advised of the development.
"We've had no justice at all", he said.
"We haven't been told anything, why were we not told?" Mrs Strathern told TVNZ.
"What is our Foreign Affairs doing about this, absolutely blooding nothing", she said.
One of the architects of that deal, Anne Richard, the former U.S. assistant secretary of state for population, refugees and migration, told Guardian Australia the offer came from a sense in the USA that the situation on Nauru and Manus Island was "bad" and they expected Australia to "do more" to help other refugees in return, including central Americans in Costa Rican refugee camps.
Politico reported that Australia refused to take the third alleged murderer, Francois Karake, possibly because he was involved in a physical altercation with a United States jail guard in 2015.
The Home Affairs Department has so far refused to comment on the report, but Immigration sources have confirmed to the ABC that the two accused murderers were settled in Australia a year ago.
While the deal was accepted by Mr Turnbull and President Obama, current US President Donald Trump was angered by the deal - as he doesn't believe it's in the country's interest.
President Trump expressing his views on the deal during an intense phone call with Mr Turnbull in 2017.
Asked to confirm the transfer on Thursday, a government spokesperson issued a statement that did not dispute the report.
"Australia does not and has not taken anyone who has failed character or security screening by our agencies under our refugee and humanitarian programme".