The union for corrections staff says it had been raising concerns about staff conduct at Rimutaka Prison before a police investigation which uncovered alleged corruption.
Six people have been charged with corruption and bribery after a three-year investigation by police into the Upper Hutt jail.
Corrections staff were allegedly bribed with sex and money to take contraband into the prison.
Corrections Association president Floyd de Plessis told Morning Report they had no direct involved in the police investigation but supported their members in talking to police, with more than 200 interviews completed.
"There was no communication or connection with us at all - from either the Department [of Corrections] or the police - so we definitely took, very much, a backseat," de Plessis said.
"The only connection we had was before Operation Portia landed, on a number of occasions, us through our members had raised a number of concerns where wrongdoing was identified, and we felt nothing was being proactively done to address that," he said.
"We had a number of situations where staff had reported wrongdoing or situations where they felt something might be happening, and in numerous of those examples, there was either nothing done or the behaviour was completely minimised and ignored."
"There does need to be better monitoring" - Corrections Association president Floyd du Plessis
Corrections chief custodial officer Neil Beales told Checkpoint staff concerns had not been properly dealt with.
Beales said Corrections needed to make sure there was a process for such reports to be investigated, because the longer a problem went, the less faith staff had it would be resolved.
"We need people to feel they can go right to the top if they need to be, and then you need to have open communication and not have systems that are so closed off that people feel unwilling or scared to raise issues."
A report by a team of independent inspectors from 2017 found Corrections staff at Rimutaka were overly familiar with inmates and did not show enough discipline with them. De Plessis said environments like that that did contribute to wrongdoing.
"So we had raised a number of concerns around some of the initiatives that the previous government put into place to basically soften the approach that we have and to have a far too familiar interaction, and so this is something we do need to change and look at, because at the end of the day we do a task and are there for safety and security, and there does need to be clear boundaries between staff and prisoners."
There was a lack of training for staff in communication and integrity, which the union had been pushing the department to do, de Plessis said.
"The level of integrity training has reduced despite these incidents happening.
"But at the same time, there does need to be better monitoring and better engagement from the department, when these thing happens, to stamp them out quickly and prevent them from happening at all."
Although the investigation had cleared the majority from wrongdoing, Corrections union members were upset by the situation, because it brought their name into disrepute, he said.
"The reality is [there are] thousands of Corrections staff across the country that do a really hard job, and they do it because they're proud of the work they do."