Papua New Guinean police have suggested Australia is carrying out "a major cover-up" over the Manus Island riots and have denied any of their officers were involved in the violence.

In an extraordinary development that underscores the gulf between PNG authorities and the Australian government, PNG police deputy commissioner Simon Kauba attacked the "lack of co-operation" from Australian government agencies in a statement released Wednesday night.

As foreshadowed by Fairfax Media earlier this week, Mr Kauba said that PNG police "did not enter the detention centre either before or during the disturbance and were not involved in the riot, nor were they responsible for inflicting any injuries sustained by the asylum-seekers".

This directly contradicts the findings of Robert Cornall, the former senior Australian public servant whose official report into the violence of mid-February Immigration Minister Scott Morrison was released on Monday.