Brown has been calling for a full investigation into how the riot started and why it has been allowed to continue.
Six prison vans have left the facility this morning and a number of Fire and Emergency vehicles have gone onto the prison grounds.
A former Waikeria Prison guard, who does not want to be identified, has told RNZ the culture is toxic and conditions are poor.
They resigned a few years ago and described the water being in an atrocious state, and staff not even touching it.
The former prison guard said the yard where inmates exercise was so run down, if it was a zoo yard it would be shut down.
They also said there's racism and an underlying negative culture towards the inmates.
In its latest statement issued last night, Corrections said the prisoners had broken into a restricted area and constructed makeshift weapons that could be used against prison staff.
The department said the prisoners have continued to cause extensive damage to the facility.
Incident controller Jeanette Burns said it is worrying that the men have gained access to weapons and equipment.
She said negotiations are ongoing and the prisoners have had multiple opportunities to surrender.
Family members of one of the 16 prisoners staging the protest have arrived at the gates.
RNZ's reporter, who is at the prison, said yelling could be heard from inside the low-security prison gates.
- RNZ
