The UNHCR has told an inquiry into allegations of abuse in Australia's offshore detention centres that the government's policies are undermining the global refugee system.

"The UNHCR have made it clear that by denying refugees access to Australia, the government is weakening the international framework to resettle refugees," Greens Immigration spokesperson Senator Nick McKim said.

"They have submitted that Australia has deliberately exposed people to harm, and failed to meet our legal obligations."

The Department of Immigration and Border Protection has confirmed that the US is not obliged to accept a particular number of refugees, or indeed any, under the terms of its "deal" with the Australian government.

"We  learned today that the agreement provides no certainty whatsoever for the men, women and children that Australia has detained on Manus Island and Nauru," Greens Immigration spokesperson Senator Nick McKim said.

The federal government's must end its secrecy over its "deal" with the United States to resettle refugees from Manus Island and Nauru.

"The government's lack of information about this arrangement is causing significant anxiety to people detained on Manus Island and Nauru," Greens Immigration spokesperson Nick McKim said.

"Prime Minister Malcolm Turnbull needs to reveal how many people will be resettled in the United States, under what conditions, and how long will it take."

The federal government's announcement of a deal with the United States is an admission that offshore detention has to end, but still leaves people on Manus Island and Nauru facing an uncertain future.

"After three years, the government has finally admitted that offshore detention is a dead-end, but has offered no certainty that people will not be left behind to languish on Manus Island and Nauru," Greens Immigration spokesperson Nick McKim said.

The federal government should be resettling people detained in camps on Manus Island and Nauru in Australia.

"Of course our hearts would lift to see people out of the camps, but they are Australia's responsibility and should be brought here," Greens Immigration spokesperson Senator Nick McKim said.

"Reports of a deal with the US lack any detail whatsoever, but the idea of sending Muslim refugees to Donald Trump's USA raises some concerns."

"We also have no idea what would happen to people detained in the camps who have not been found to be genuine refugees."

Labor's crawl towards a more compassionate approach to refugees does not change their continued support for cruel and ineffective policies, Greens Spokesperson for Immigration Nick McKim says.

"These are baby steps only, and Australia needs this to be the beginning of a more compassionate and humane approach to people seeking Australia's protection," Senator McKim said.

"It’s time for Labor to add some vertebrae to their newly formed spine and reject offshore detention and boat turnbacks."

It's time for Labor to grow a spine and reject the government's latest deliberate cruelty against refugees, Australian Greens Immigration spokesperson Nick McKim says.

"Labor should not need to wait for the legislation to land before deciding whether it has the strength to take a principled stand," Senator McKim said.

“They need to decide whether they are going to line up with the Coalition and One Nation, or whether they have the compassion and strength to vote this hateful legislation down.”

The Government has sunk to a new low in its latest attempt to punish innocent people seeking asylum, Australian Greens Immigration spokesperson Nick McKim says.

"The proposed new laws are an escalation of the cynical race to the bottom which sees our fellow human beings again used as a tool to seek domestic political advantage," Senator McKim said.

"This is about absorbing nothing more than One Nation votes."

"People are languishing on Manus Island and Nauru because of the government's incompetence and refusal to find a solution."

The Greens have welcomed the removal of the Border Force Act gag on doctors, but have called for it to be removed from all other detention centre workers and contractors.

"This is a humiliating backdown by the Government and an admission that all departmental workers and contractors were in fact gagged by Section 42 of the Border Force Act," Australian Greens Leader Senator Richard Di Natale said.

"This gives the lie to the government's claim that workers and contractors are protected as whistle-blowers."