Human rights group Amnesty International has found the Australian Government downplayed the danger asylum seekers on Manus Island faced when the detention centre was attacked by soldiers from the Papua New Guinea Defence Force.

Amnesty analysed photos and videos from the centre purportedly taken during the attack on Good Friday — April 14.

They showed bullets were fired into the accommodation area of the centre that night — directly contradicting the Government's claims, in a statement from the Department of Immigration and Border Protection, that they were fired into the air, the report found.

"I think we can say with a degree of certainty now that multiple shots were fired into the centre and that put people at risk," researcher Kate Schuetze said.

"What we've had here was a very serious incident of violence outside the centre.

"It's not the first shooting which has occurred at the Manus Island centre and it's of course the second time now that the centre has been under attack from the outside, which really proves that the Australian Government and the Papua New Guinean Government cannot protect the safety of refugees and asylum seekers there."

The human rights group said it had analysed 21 photos and six videos purportedly taken from inside the centre the night of the attack.

"The digital experts used reverse image search tools and corroboration with known photos of the centre to geolocate the images," the report said.

"A military expert also reviewed the images and videos."

Sorry, this video has expired Reports of shots fired at Manus Island detention centre

Ms Schuetze said it appeared the Government sought to minimise the perceived risk to asylum seekers.

"We've had a lot of information come out very quickly, trying to downplay not only the incident and the risk that refugees were put in, but also to try and deflect attention from the actual causes around what happened," she said.

'Ultimately a matter for PNG Government', Immigration Department says

The Department of Immigration and Border Protection said Amnesty International did not consult it about the report or seek a response.

"Consistent with previous Amnesty International reports, the Department has not been consulted nor provided an advance copy of this report," it said in a statement.

"While this is ultimately a matter for the PNG Government, we cannot comment on a report we have not seen."

The PNG Police and the PNG Defence Force are separately investigating the attack.

They are yet to announce any arrests or disciplinary action against those involved.

But extra police officers are being deployed to the centre — not because of the increased tension, but to help Australian and PNG authorities force some of the men inside to relocate to a so-called "transit centre" closer to the main town on Manus Island.

Australian Border Force deputy commissioner Mandy Newton told PNG's National Broadcasting Corporation that police would help prevent any unrest during the relocation.

"Because we don't want any trouble to occur, we don't want any rioting to occur," she said.

"We want to consult with the people in the centre — which we have been doing now for some years — but it's important also that people know that they can't behave inappropriately, either in the community or within the centre."

There are still more than 800 men in the Manus Island detention centre. ( Reuters )

There are still more than 800 men in the Manus Island detention centre, and roughly another 80 living in the transit centre or elsewhere in PNG under a resettlement agreement.

Of those, about 700 have been found to be refugees and are eligible for resettlement in the United States or PNG.

There were 160 men in the centre whose refugee claims failed.

They have been told to return to their countries of origin, and some who refused have already been deported.

Refugees in the centre say officials from the US Department of Homeland Security were on the island recently, but only interviewed between 60 and 80 people.