Thousands of Australians have taken to the streets in protest as the United Nations calls on the Australian Government to care for the 600 men who refuse to leave the Manus Island detention centre and are going without food, water or medical care.

UN High Commissioner for Human Rights, Prince Zeid bin Raad al-Hussein, on Saturday described the situation at the decommissioned Papua New Guinea processing centre as an “unfolding humanitarian emergency”.

Soon after Prince Zeid’s statement, thousands of Australians in Melbourne and Sydney marched for an end to the stand off, with Greens MP Adam Bandt telling a Melbourne crowd Immigration Minister Peter Dutton was “a terrorist”.

Refugees have refused to leave the Australian-run facility at Manus Island that officially closed on October 31, fearing locals near replacement accommodation located at Lorengau will attack them.

“We have serious concerns about the welfare, safety and wellbeing of the roughly 600 men who remain in the accommodation compound, who are too frightened to leave,” UN High Commissioner for Human Rights Rupert Colville said.

Mr Colville said the men feared they would be subjected to violence at the hands of locals if they leave the compound.

“…Given there have been violent incidents in the past, we believe these fears should be respected and satisfactorily addressed,” Mr Colville said.

“We urge the Australian Government to transfer the men to mainland Australia where their claims can be processed.”

Melbourne #flindersst intersection shut down #EvacuateManus #Manus #Bringthemhere #auspol Solidarity to the men on Manus pic.twitter.com/indvkoiy9U

— WACA (@akaWACA) November 4, 2017

On a wet Saturday afternoon, Sydney says #BringThemHere #refugee #Manus #humanitariancrisis #auspol pic.twitter.com/yzMyhaUYfc

— Simon Cadman (@CadmanSimon) November 4, 2017

Recorded messages from men inside the Manus Island detention centre were played to the Melbourne rally.

The two men described their situation, in which they said they found themselves without basic provisions or medical supplies following the centre’s closure.

“We are forgotten people who have been tortured … even though we have committed no crime,” one of the men said in his message.

“Our situation is getting worse and we need your help,” the other man said.

“Will Australians stand up and speak for humanity if you think refugees are humans?”

Opposition Leader Bill Shorten said there was “something going on at Manus (Island), which is deeply disturbing to the Australian people.”

Mr Shorten said Prime Minister Malcolm Turnbull must ask President Donald Trump to speed up the resettling of refugees in the US as the stand-off entered its fourth day on Saturday.

Refugees have been stockpiling water and digging wells into the night to access water. The last food packs were distributed last Sunday.

PNG Defence Forces have reportedly turned away ‘good Samaritans’ trying to deliver food to the hungry refugees.

Journalist Behrouz Bochani, an Iranian refugee held on Manus Island since 2014, said days at the “prison” were “unbearably torturous” and characterised by the “survival of the fittest” in an article published by The Guardian.

Mr Bochani said detained refugees had gathered a few litres of rainwater, boiled it and mixed in sugar to offer something to eat.

“Starvation, thirst and terror slowly but surely dominate the prison,” he wrote.

The commanding officer of the Lombrum naval base, where the detention centre resides, has assured no “arbitrary action” would be taken on the remaining refugees, but said they would be forcefully removed if necessary.

“They are here at the military camp and most of their base in military camp are out of bounds to any civilian and they will not be seen wandering around in the camp, but if anything happens, with instructions from headquarters, we can act,” Mr Karaki told PNG newspaper the Post Courier.

New Zealand has confirmed the country is prepared to accept 150 refugees from the island with Opposition leader Bill Shorten urging Prime Minister Malcolm Turnbull to accept the proposal.