Internal Immigration Department documents released to the media showed the extent of the incident between PNG police mobile squad and the PNG army on October 18.

Australia's federal Opposition and the Greens have accused the government of a cover-up after staff members were evacuated from the centre amid the violent confrontation.

Reports suggested firearms were drawn, sticks and rocks brandished, and there were fears security at the centre could be breached.

Opposition immigration spokesman Richard Marles said: "This goes beyond the culture of secrecy - it would appear that it is in the realms of a cover-up.

"This is not about preventing the release of information for operational reasons, it is about preventing the release of information because it does not suit the government," he added.

"What is absolutely clear is that the Australians felt their security was compromised and that makes it a matter of public interest to Australians."

Greens immigration spokesman Senator Sarah Hanson-Young said the government was trying to pull the wool over the Australian publics' eyes.

"Scott Morrison has been caught lying to the Australian public about the attack that put vulnerable refugees and Australian staff at risk," she said.

"When Parliament resumes I will move for an independent inquiry into the incident. Australians deserve a full explanation as to what is happening in this taxpayer funded centre.

"It's concerning that this operation is putting Australian workers at risk, especially now that we know where Scott Morrison and Tony Abbott's priorities actually lie after they tried to cover up the seriousness of this incident.

"This violent clash would have been terrifying for all of those involved, particularly the refugees who were left behind confused and frightened for their lives, and my thoughts go out to them."