The union representing prison officers says Serco is dodging responsibility by saying it only received a report in May on allegations of a fight club at Mount Eden Correctional Facility.
Yesterday, Serco's director of operations, Scott McNairn, said it received the relevant parts of the Departments report on allegations of organised fights in prisons only two months ago.
Corrections Association Industrial officer, Beven Hanlon, said that was a poor excuse for doing nothing.
"Serco weren't involved in the investigation but the investigation happened at their prison.
"There were two people that don't work at their prison in their prison talking to prisoners, staff and managers.
"They knew it was happening so they must have been expecting some sort of result from it," he said.
A Western Australian organisation that opposes Serco running a major prison in Perth said it was not surprised by that response or by the problems at Mount Eden
Serco runs both Acacia Prison - one of the largest jails in Australia - and Wandoo Reintegration Facility - a minimum security prison for young men, in Western Australia.
Colin Penter is the convener of the network, Serco Watch, a group against privatisation of public services such as prisons and hospitals.
He said as Serco was a private company, incidents such as fight club allegations could have been kept quiet by the company and its employer for financial reasons.
"What happens in a lot of Serco's contracts is these incidents occur but they're kept secret because if you report the incident it is abated or fined.
"So what happens of course is they don't report these incidents.
"The interesting thing is that it requires some external or third party or in this case a video before we find out about these incidents," he said.
Mr Penter said private prisons often had low staff numbers to ensure maximum profit.
And he doubted Serco staff would have both the capability or the will to intervene in a fight club situation.
Warning: the video below contains graphic images, which may be disturbing to some viewers.
Mr Hanlon agreed.
"You can't blame the staff for not doing anything, mainly because there were no staff to do anything," he said.
The Public Service Association represents 100 staff at Serco's two private prisons, Mount Eden and Auckland South Correction Facility.
National Secretary Erin Polaczuk said a fight club would be less likely if prisons were state run.
"When your motive is for profit you're going to have to figure out ways to cut costs.
"In the case of prisons, what they've done is they've figured out they can cut costs by having fewer guards on or having prisoners locked up for longer.
"And in either of those scenarios you're going to end up with dangerous situations for members and for the prisoners," she said.
Behavioural coach and former inmate Paul Wood said fighting in prisons as exposed at an Auckland jail was nothing new, but it was harder to dismiss because there was video footage.
He spent 11 years in prison for murdering his drug dealer at the age 18, and said prisons were extremely violent places.
''I think the big difference here is that this is something visual and therefore far harder to ignore.
"I think there have always been stats available on the prevalence of violence and assaults in prisons.
"It's a bit harder to to dismiss it when it's actually this real for people."
Head of Corrections Ray Smith said senior Corrections staff were now working with Serco management at the prison.
Mr Smith said he only saw the report last Saturday.
While Corrections Minister Sam Lotu-Iiga said he had only received the report on Saturday and that Prime Minister John Key was only advised of the report on Sunday night.
"The first thing we've got to do is lets understand whether they've breached their contract, lets fully understand whether its them, how widespread it is, and if they have what penalties we can actually impose under the contract, I know there's certainly financial penalties," Mr Lotu-Iiga said.