An increasing number of complaints raised about the goings-on at Mt Eden Prison has meant the deadline for the report into the Serco-run remand prison has been extended.
Pushing back the reporting date has led the Green Party to question why the Government hasn't cancelled the contract altogether.
Corrections chief executive Ray Smith says the terms of reference of the inspectorate report into fight clubs at the privately run prison have also been widened.
He says the changes will allow the chief inspector to review a number of complaints from prisoners and their families which have come to light since the investigation was launched on July 19.
"It is essential that the investigation is comprehensive given the level of public interest in the operation of [Mt Eden prison]. The safety of staff and prisoners is our top priority," Mr Smith says.
It is now expected phase one of the report will be done by October 30, with the second report pushed back until November 30.
Phase two of the review will consider the adequacy of controls designed to address prisoner violence and access to cellphones in other New Zealand prisons.
The initial review was launched following video emerging from the prison of fight clubs, and later of drug-taking and drinking, as well as claims a prisoner died after receiving injuries from being dropped from a balcony.
Earlier this week, Corrections Minister Sam Lotu-Iiga said a prison guard had been giving prisoners advice on how to spar after CCTV video apparently showed him fighting with inmates.
Corrections used a clause in its contract with the company to step in to manage the prison, which will still continue to be the case while the investigation is being completed.
Greens corrections spokesman David Clendon says stepping in is "no longer enough".
"You really have to wonder why Corrections are just sitting on their hands and refusing to issue the final warning."
He questioned whether Mr Lotu-Iiga not pushing for a final warning was an admission the privatisation project had failed.
Labour's corrections spokesman Kelvin Davis says he's not surprised by the extension given the "tsunami of complaints" his office had received.
The investigation being pushed out as a result of the flood of complaints and revelations since it began is another example of Mr Lotu-Iiga not handling the "shambolic" situation, Mr Davis says.