The investigation into organised prisoner fighting at Mt Eden jail has been extended by two months because of the high number of complaints from prisoners and their families.
The final report on the first phase of the investigation was due tomorrow but will now be completed by the end of October.
The first phase is looking at the circumstances of fights between prisoners, access to cellphones and the adequacy of reporting on incidents of prisoner violence.
Department of Corrections chief executive Ray Smith said the extension would give the Chief Inspector of Prisons time to review the complaints.
Corrections took over the management of Mt Eden prison from private operator Serco last month.