Tensions over the migrants have grown since the governments of Australia and Papua New Guinea agreed in April to close the site by Oct. 31.
On Tuesday, water and electricity to the camp were shut off, and detainees were supposed to move to temporary housing in Lorengau, a city close by on the island.
Many of the men refused, citing previous attacks by residents in Lorengau. Instead the migrants barricaded themselves inside, using solar power for their phones and digging wells for water as police cars circled.
“It’s very surprising to see it come to this level,” said Jonathan Pryke, Pacific Islands program director for the Lowy Institute, an Australian think tank. “It just seems like a complete mess.”
One detainee, Behrouz Boochani, a Kurdish journalist from Iran, said the men were experiencing dehydration, hunger, anxiety and the fear of attack and disease.
“Heat, humidity, hunger and incessant mosquitoes are taking their toll,” Mr. Boochani wrote on Facebook. “This is not a hunger strike. It is a situation that the Australian government has created, forcing people into starvation and these harsh conditions by refusing to offer a safe place for resettlement.”
The governments of Australia and Papua New Guinea each claim the other is responsible for relocating the men until a permanent solution can be found.
Australia has pledged 250 million Australian dollars, or $193 million, for the men’s food and security at the facilities in Lorengau for the next year.
Julie Bishop, Australia’s foreign minister, said on Thursday that it made “no sense” for the detainees to remain at the camp. But Nat Jit Lam, the regional representative of the United Nations’ refugee agency, said the temporary housing was incomplete and unsafe.
“I will not be bringing any refugee there to stay — not in that state,” Mr. Lam told ABC Radio of Australia.
In a statement issued Thursday, the agency said: “Australia remains responsible for the well-being of all those moved to Papua New Guinea until adequate, long-term solutions outside the country are found.”
Australia has consistently said it will not accept the men for resettlement.
They have all been given the option of permanent residency in Papua New Guinea, or applying to resettle in Cambodia or Nauru, the location of a second offshore facility run by the Australian government. None of the men still on Manus have accepted the offer, according to reports.
American officials said dozens if not hundreds of refugees from Manus and Nauru would be accepted in the coming weeks and months. About 50 men already moved to the United States in September under a deal brokered by former President Barack Obama.
Jacinda Ardern, the new prime minister of New Zealand, also said this week she would an honor a predecessor’s pledge to accept 150 refugees. The Australian government has been reluctant to allow New Zealand to accept the men, fearing it would open a legal backdoor to Australia.