The Corrections Department has been investigating claims of organised fights at the Serco-run Wiri Prison, Labour says.
Serco lost its contract at Mt Eden Prison in July last year but was allowed to keep its contract at Wiri.
A report out yesterday into incidents at Mt Eden when Serco ran it said weekly fight clubs run by gangs took place and contraband was "freely available" from staff.
Labour Party corrections spokesman Kelvin Davis said when he visited Wiri Prison last week several prisoners told him fight clubs were taking place there almost daily.
He said he went to the head of Corrections, Ray Smith, with the allegations.
Mr Davis said he has received a letter from Mr Smith saying he had looked into it and received assurances that fighting was not commonplace, and that any incidents of violence that staff knew about were investigated and dealt with.
In the letter, Mr Smith said he had received similar assurances from the department staff who were monitoring the prison.
Mr Smith said he had recently visited the prison and his impression was that the prison was working well and staff were handling incidents properly.
"Now normally I would expect a two or three or four week turnaround on that sort of investigation," Mr Davis said.
"But I got a letter earlier this week dated the 5th of October saying, 'look I've looked into it, the monitors say that nothing is happening and Serco say that nothing is happening'," Mr Davis said.
Mr Davis said, given how poorly Serco ran Mt Eden Prison, Wiri should also be investigated.