More than 600 refugees and asylum seekers are spending another night inside the former immigration detention centre on Manus Island after the United Nations high commissioner for refugees backed up reports that accommodation on the island is “not ready” for detainees being kicked out of the centre.

Electricity and all essential services were switched off this week and all centre staff have also left. Refugees and asylum seekers inside the centre have held daily peaceful protests for more than three months.

The men refuse to move into an accommodation centre in the nearby Lorengau community, saying they fear for their safety. Human Rights Watch recently detailed an upsurge in violent attacks on refugees and asylum seekers by groups of armed locals.

On Tuesday there were multiple reports of looting by locals after staff abandoned the centre.

The Australian immigration minister, Peter Dutton, accused the detainees and advocates of “subterfuge” in their claims of safety concerns, and the acting prime minister, Julie Bishop, said detainees would be provided with shelter, food and medical care at the three Lorengau accommodation units.

But on Wednesday Nat Jit Lam, regional representative for the UNHCR, said he had inspected two of the three sites and the accommodation at West Lorengau was not ready.

“There was still major earthworks in progress,” he told ABC radio. “There was heavy machinery on the ground as well, fences still being constructed.”

“It doesn’t look like it’s ready. I’m not an expert on engineering but, as a UNHCR officer who’s been working with refugees, I would not be bringing any refugees to stay there, not in that state. It’s not ready at this moment.”

The UNHCR claims support reports from Amnesty International and the Australian Greens senator Nick McKim.

McKim, who is on Manus Island, told the Guardian that Dutton was “bullshitting” about the readiness of accommodation and that he had since learned there was also a shortage of about 150 beds in the new units.

“So even if all the guys came out today there would be 150-plus of them who would be left on the side of the road in Lorengau, where there have been brutal attacks,” he said on Wednesday.

Refugees reported seeing suspected Australian officials outside the centre, and said PNG immigration and security officials had spoken to them through the fence.

The ABC reported an increased military presence around the centre, with one soldier saying they were acting as security after Tuesday’s looting.

Behrouz Boochani, a Kurdish Iranian journalist and refugee, said there had been one instance of self harm among the group, but that the man was being cared for. Another had health complications, he said.

Detainees were given extra medication ahead of the closure but McKim claimed many had now run out and were going through withdrawal from psychotropic medication.

If Navy attacks us Australia is responsible. We didn't come to this island by our will. You cannot kill people who are resisting peacefully. — Behrouz Boochani (@BehrouzBoochani) November 1, 2017

Boochani said detainees had stood watch during the previous night, in anticipation of action by locals or authorities.

PNG immigration officials have said they will not forcibly remove detainees on Wednesday, but detainees have little food and water, and no working sanitation.

“All refugees woke up again in fear and scared what might happen, there is no water, power and food,” Aziz Adam told the Guardian from inside the centre. “Even the toilets do not work. People are stressful and anxious. Any time we expect the navy might come in.”

The centre sits within a PNG naval base, which officially has control over the site. On Good Friday, drunk soldiers fired their weapons at the centre after an altercation with some refugees. Detainees and staff cowered inside or fled into the nearby jungle.

Accommodation units are not the only point of contention. The PNG and Australian governments are also in a developing stoush over who has responsibility for the refugees and asylum seekers who can’t or won’t settle in PNG.

PNG has said it has fullfilled its obligations to the 2013 offshore processing agreement between the two countries, and Australia had to fund all services for remaining detainees, and find third country resettlement options for them.

Australia has said it is a matter for the sovereign PNG government, however it has also repeatedly refused an offer from New Zealand to take some people.