The head of the United Nations' refugee agency has accused the federal government of backtracking on an understanding to resettle some people on Manus Island and Nauru in Australia.
Filippo Grandi, in a statement released on Monday, said UNHCR had agreed to help with the relocation of refugees in offshore detention to the United States last November.
But that was based on the "clear understanding" that vulnerable refugees with close family ties in Australia would ultimately be allowed to settle there.
"UNHCR has recently been informed by Australia that it refuses to accept even these refugees, and that they, along with the others on Nauru and Papua New Guinea, have been informed that their only option is to remain where they are or to be transferred to Cambodia or to the United States," he said.
That meant, for example, some with serious medical conditions or who've experienced trauma including sexual violence can't get support from family in Australia, the UN's high commissioner for refugees said.
"To avoid prolonging their ordeal, UNHCR has no other choice but to endorse the relocation of all refugees on Papua New Guinea and Nauru to the United States, even those with close family members in Australia."
But in an interview with the ABC, the UNHCR Assistant High Commissioner for Protection Volker Turk said the organisation never had an explicit agreement with Australia regarding its resettlement plan.
"We had broad agreements and understandings of how the UNHCR would actually be part of facilitating the implementation of the agreement that was reached between Australia and the United States," he said.
"There was no doubt in our mind that - and this is what we put forward to the minister at the time - that we would present to him cases that are compelling, humanitarian, and with close family links with Australia.
"We were hoping that indeed Australia would consider them favourably within the discretion that the minister has at his disposal."
Mr Turk said Immigration Minister Peter Dutton never gave any assurance to the UNHCR about resettling asylum seekers because the organisation hadn't presented any cases yet.
The Turnbull government has always publicly insisted that no one in offshore detention will ever come to Australia.
Mr Dutton on Sunday said there was no contingency under which the government would change its mind.
"No, and people will not be coming to Australia," he told Sky News.
A spokesperson reiterated the point on Monday, saying those transferred to offshore processing centres will never settle in Australia.
"The position of the coalition government has been clear and consistent."
Mr Grandi said there was no doubt vulnerable people - already subject to four years of "punishing conditions" - should be reunited with their families in Australia, labelling it the humane and reasonable thing to do.
"The Australian government's decision to deny them this possibility is contrary to the fundamental principles of family unity and refugee protection, and to common decency," he said.
He urged Australia to bring an immediate end to the harmful practice of offshore processing, claiming it has caused extensive and avoidable suffering.
His sentiments have been echoed by Amnesty International and the Asylum Seeker Resource Centre, who have called on the Turnbull government to reunite those families who have been split up.
