Twelve former Australians of the Year have written an open letter pleading with the Prime Minister to allow medical professionals access to asylum seekers inside the recently closed Manus Island detention centre.
"It's really likely that deaths will occur in the coming days and weeks so something needs to be done," mental health expert Professor Patrick McGorry said.
"There's a great concern about the safety of these men from both a medical and a psychiatric point of view."
More than 400 asylum seekers have shut themselves inside the Australian-run centre for three weeks, defying attempts by the Federal Government and Papua New Guinea to close it.
The Australian Medical Association voted unanimously on the weekend to call on the Government to let their doctors onto Manus to assist the men left inside, but so far access has not been granted.
"We, as former Australians of the Year, representing the hearts and minds of the nation, are deeply concerned about the health and human disaster that is unfolding on Manus Island," the open letter read.
"In the coming days, it is inevitable that people will become sick and even die through the lack of basic sanitation, food, water and medical care."
'We're all unified'
The signatories include media doyenne Ita Buttrose, legal academic Professor Mick Dodson, and social entrepreneur Simon McKeon.
Professor McGorry said it was unprecedented for so many former Australians of the Year, from different walks of life, to unite on one issue.
"The weighting of the Australians of the Year is made up of health and medical experts who share this urgent concern for the safety and welfare of these men," he said.
2015 Australian of the Year Rosie Batty said she wanted the letter to send a strong message to the Government.
"I hope it shows that all of these previous Australians of the Year from different backgrounds … we're all unified in our absolute abhorrence of Australia's handling of this situation," Ms Batty said.
"The obvious honour that we've all shared and the acknowledgement for the work we've done, we hope that would give a lot of credibility to the strength of feeling that there are so many Australians who feel the same way."
More than 400 asylum seekers left
The 421 asylum seekers on Manus Island said they feared violent reprisals from the community if they move to transit centres, pending possible resettlement to the United States.
The United Nations High Commissioner for Refugees said centre's conditions were deteriorating rapidly it was a humanitarian crisis.
On Wednesday, Foreign Minister Julie Bishop rejected the UN's criticism and said the men are simply trying to put political pressure on the Australian Government.
"There is accommodation that is perfectly acceptable, indeed many people have moved there already," she said.
"Those who have stayed on Manus Island are doing so to try to force Australia to take them."