The UN's refugee agency has accused Australia of reneging on an agreement to reunite some refugees with relatives already living in the nation.
The "clear understanding" had been part of a wider deal to resettle refugees in the US, the agency said.
It said Australia had recently backed out of that understanding. Australia has said no such promise ever existed.
The UN agency said Australia's long-held policy of detaining asylum seekers offshore had caused "extensive" harm.
Australia has controversially refused to accept asylum seekers and refugees, most of whom are men from Iran, Afghanistan and Iraq, and instead holds them in centres on the Pacific nations of Nauru and Papua New Guinea.
The government has said its policy disrupts people smuggling and prevents deaths at sea.
On Monday, the UN high commissioner for refugees (UNHCR), Filippo Grandi, said Australia had only recently confirmed that it would not take refugees with existing close family ties.
"This means, for example, that some with serious medical conditions, or who have undergone traumatic experiences, including sexual violence, cannot receive the support of their close family members residing in Australia," he said.
However, the Australian government denied it had offered to accept any of the refugees, saying its policy had been "clear and consistent".
"Those transferred to RPCs [regional processing centres] will never settle in Australia," a government spokesperson told the BBC.
Under existing agreements, refugees have the possibility of settling only in Nauru, Papua New Guinea, the US, Cambodia, or another nation where they are eligible to live.
Criticism of detention
Mr Grandi said reuniting families was "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.
Many people had suffered "physical and psychological harm" since Australia introduced its current policy in 2013, he added.
In April, the US confirmed it would go through with a deal to resettle up to 1,250 refugees - which Australia had arranged with the Obama administration.
US President Donald Trump had called the deal "dumb" following a phone call with Australian PM Malcolm Turnbull.