In handing down the independent report into the violence on the island's detention centre during February, Mr Morrison said the two days of violence was "terrible, tragic and distressing".

The report said the violence against the detainees was carried out by members of the PNG police "mobile squad", G4S guards - mostly locals but also some expatriates - locally employed Salvation Army workers and some Manus residents.

It said Iranian asylum seeker Reza Barati, 23, died from a severe brain injury caused by a brutal beating by several assailants. It maintains the attack was led by a Salvation Army worker who was a PNG national.

In the brutal violence, another asylum seeker also had his throat slit, Mr Morrison confirmed, saying he was lucky to be alive today.

Mr Morrison said recommendations made by the head of Operation Sovereign Borders, Lieutenant General Angus Campbell, for better fencing, CCTV footage and lighting at Manus Island's detention centre had not been implemented by February, despite the minister asking for the improvements in November.

"There were actions taken over many months to try to mitigate against an event of this nature," he said.

"We took every action we could as quickly as we could. But it is my great regret that some of those actions weren't able to be implemented in time.

"I'm frustrated that that the lighting and the CCTV and the fencing was not in place at that time. It was in the process of being done. I'd authorised that in late November. The previous government had been advised of that and had done absolutely nothing."

He added the report by former senior public servant Robert Cornall did not attribute the riots to any single cause but rather a combination of issues.

Mr Morrison said there were numerous attacks on Mr Barati, 23, including him being beaten by a Salvation Army worker, before being kicked by a G4S security contractor and "other individuals" who also smashed a rock into his head.

"Now these are terrible acts and there is no suggestion that this was a proportionate response to the events," he said.

The report has made 13 recommendations including to support Papua New Guinea's investigations into the violence, to assist Transfield in providing welfare to asylum seekers and to better inform asylum seekers of their refugee status determination.

Crucially, the report said that the two most important things to avoid such violence again were to prevent the tension from allowing to build to "a dangerous level" and to ensure the security infrastructure such as fencing was improved.

The report stated that tension had been building in the centre because the asylum seekers were angry about being brought to PNG and also about the lack of information they were being given about their futures. There were also racial tensions between them and the locally-employed guards.

This tension "reached a flashpoint" after a meeting between community leaders among the detainees and centre staff including immigration officials from PNG and Australia.

"The transferees felt that, after waiting for 12 days, they were given no new information at the Sunday meeting and that their questions had not been satisfactorily answered," the report said.

On the first night of the violence, an asylum seeker was attacked "from behind" by an unidentified local G4S guard who slashed his throat, causing a 10 to 12 centimetre "gaping wound".

Mr Morrison said the man was lucky to be alive and was saved only by the fact that the blade hit no major blood vessel.

On the second night of violence – the night in which Mr Barati was killed – the G4S incident response teams "worked as hard as they could". But the team holding the main line at Mike compound was forced to pull back, after which the PNG police mobile squad went in, followed by guards and locals.

"After the IRT left and without any warning to or arrangement with G4S, the mobile squad pushed over the fence and entered Mike," the report states.

"The review was told that PNG nationals and a few expatriates, some identified as service provider employees, followed the mobile squad into Mike compound and started bashing transferees," the report states.

It says the initial attack on Mr Barati was led by a PNG local worker for the Salvation Army, according to an eyewitness who said other witnesses could corroborate his version. The identity of the Salvation Army worker is known to authorities.

The witness said the worker hit Mr Barati twice from behind "with a very long stick". More than 10 other guards and workers kicked Mr Barati in the head as he lay on the ground.

Then a PNG local guard hit him on the head with "a very big stone", the witness said.

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