Papua New Guinea authorities say they have moved all of the remaining 328 men at the decommissioned Manus Island detention centre to new camps, after police and immigration officials re-entered the site on Friday morning.

Key points: PNG authorities say all remaining men at the centre have been moved to new housing

PNG authorities say all remaining men at the centre have been moved to new housing Refugees report being beaten by police, but Dutton says claims exaggerated

Refugees report being beaten by police, but Dutton says claims exaggerated Conflicting reports on whether new sites are up to scratch

Immigration Minister Peter Dutton also confirmed the centre was now clear, a day after around 50 men were removed from the centre in a similar operation, sparking tension between police and the refugees.

The ABC saw at least 12 buses turning into the East Lorengau transit centre on Friday.

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However, it was unclear how many of the 328 men were on board and whether they all had passengers or just belongings.

"Four buses are full and on way to the new camps," refugee and journalist Behrouz Boochani tweeted earlier, adding that other vehicles were carrying belongings.

"The refugees are saying that they are leaving the prison camp because police are using violence and very angry."

Mr Boochani said he had seen PNG police beat several asylum seekers and refugees during the operation to clear the centre.

"[On Friday] they beat some of the refugees, so that was not peaceful," he told the ABC.

Images uploaded to social media show men with angry welts on their backs and arms that they say came from those beatings.

A Manus Island refugee says his injuries were caused by police. ( Supplied )

A refugee on Manus Island says the welts on his body were caused by police. ( Supplied )

The United Nations' refugee agency said it had received reports several men had been severely injured and medical treatment was paramount.

"The situation still unfolding on Manus Island presents a grave risk of further deterioration, and of further damage to extremely vulnerable human beings," said Thomas Albrecht, the UNHCR's regional representative in Canberra.

However, PNG Police Commissioner Gari Baki said the relocations were done "peacefully and without the use of force".

Mr Dutton accused activists of making inaccurate and exaggerated claims of violence and injuries, and said they had failed to produce any evidence to prove the allegations.

"What is clear is that there has been an organised attempt to provoke trouble and disrupt the new facilities," he said in a statement.

Conflicting reports on whether new sites up to standard

Mr Baki said the current situation should be a "walk in the park" for asylum seekers, compared to their past lives in their home countries.

"Manus is a peaceful island and I am sure it is a walk in the park compared to what they left behind in their respective countries," he said in a statement last night.

"We are doing the best we can and the refugees cannot continue to be stubborn and defiant.

"The fact is that we are not moving them into the jungle … they are being relocated to two centres where there is water, electricity, food and medical services."

Mr Dutton said alternative accommodation had been available to house all inhabitants of the former detention centre since October 31.

"Food services, cleaning, security and the ELRTC-medical clinic are all operational and have been available since October 31," he said in a statement.

But Tim Costello, the chief advocate for World Vision Australia, said some of the new sites were not up to standard.

Mr Costello and members of his organisation have been on the island and had the opportunity to look at the facilities being offered to the men there.

Work is ongoing at the West Haus refugee housing site on Manus Island. ( Supplied: World Vision )

"I got into West Haus and I can tell you this is a construction site, this is not finished," Mr Costello told RN Breakfast.

"There is earth-moving equipment, there are open drains."

Mr Dutton said the Government had been advised that some equipment had been sabotaged and water infrastructure had been vandalised.

"The equipment is being repaired or replaced and the Government understands these matters are under investigation," Mr Dutton said.

Bishop says 'nations respect our stand'

Meanwhile, Foreign Minister Julie Bishop said the situation on Manus Island is not undermining Australia's international reputation.

"I do not believe so at all," Ms Bishop said.

"In fact nations respect our stand on people smuggling and we are working very closely with countries including Indonesia to ensure that the people smuggling trade is not revived."

Labor's immigration spokesman Shayne Neumann called on the Government to do more to find other options for the men.

He said the Prime Minister should "immediately accept New Zealand's offer to resettle refugees from Manus Island and Nauru and negotiate conditions similar to the United States refugee resettlement agreement to ensure people smugglers do not exploit vulnerable people".