Amnesty International says its experts have verified images and footage from the Good Friday shooting on Manus Island that confirm bullets were fired directly into the immigration processing centre.

The human rights group says the digital verification, expected to be released on Monday, contradicts initial claims made by Australian immigration officials and Papua New Guinea police suggesting soldiers only fired bullets into the air.

Immigration Minister Peter Dutton has repeatedly stated Papua New Guinea soldiers opened fire on the centre because they were concerned about the welfare of a young boy who was allegedly led into the compound.

The Papua New Guinea government, meanwhile, says an investigation into the Good Friday shooting is ongoing.